Sergei Sergeenkov

Pós-doutorado

Idiomas

Áreas de atuação

Produções bibliográficas

• AMARO NETO, JOSÉ ; DE S. OLIVEIRA, J. R. ; FURTADO, CLAUDIO ; SERGEENKOV, SERGEI . Quantum ring in gapped graphene layer with wedge disclination in the presence of a uniform magnetic field. European Physical Journal Plus , v. 133, p. 185-196, 2018.

• RIBEIRO, L.R. ; PASSOS, E. ; Furtado, C. ; SERGEENKOV, S. . Analogue of the quantum Hall effect for neutral particles with magnetic dipole moment. Physics Letters. A (Print) , v. 381, p. 849-851, 2017.

• Cichetto, L. ; SERGEENKOV, S. ; DIAZ, J. C. C. A. ; LONGO, E. ; ARAÚJO-MOREIRA, F. M. . Influence of substrate on structural and transport properties of LaNiO 3 thin films prepared by pulsed laser deposition. AIP Advances , v. 7, p. 025005, 2017.

• OLIVEIRA, J.R.S. ; GARCIA, G.Q. ; Furtado, C. ; SERGEENKOV, S. . Evolution of Landau levels in graphene-based topological insulators in the presence of wedge disclinations. ANNALS OF PHYSICS , v. 383, p. 610-619, 2017.

• SERGEENKOV, S. ; STAN, C. ; CRISTESCU, C. P. ; BALASOIU, M. ; PEROV, N. S. ; Furtado, C. . Evidence for field induced proximity type behavior in based ferromagnetic nanofluid. PHILOSOPHICAL MAGAZINE LETTERS , v. 97, p. 287-293, 2017.

• VIEIRA, MARCELO ; SERGEENKOV, SERGEI ; FURTADO, CLAUDIO . Gap-dependent mass of a photon in a photonic topological insulator. PHYSICAL REVIEW A , v. 96, p. 013852-1-013852-4, 2017.

• SERGEENKOV, S. ; CÓRDOVA, C. ; Cichetto, L. ; de Lima, O.F. ; LONGO, E. ; Araújo-Moreira, F.M. . Anomalous temperature behavior of resistance in C1−xCox thin films grown by pulsed laser deposition technique. Journal of Alloys and Compounds , v. 667, p. 18-22, 2016.

• SERGEENKOV, SERGEI ; AUSLOOS, MARCEL . On the electronic viscosity of a Dirac fluid in deformed graphene. Philosophical Magazine Letters (Print) , v. 96, p. 97-100, 2016.

• SERGEENKOV, S. ; Cichetto, L. ; DIAZ, J.C.C.A. ; BASTOS, W.B. ; LONGO, E. ; Araújo-Moreira, F.M. . Manifestation of unusual size effects in granular thin films prepared by pulsed laser deposition. Journal of Physics and Chemistry of Solids , v. 98, p. 38-42, 2016.

• SERGEENKOV, S. ; CÓRDOVA, C. ; ARI-GUR, P. ; KOLEDOV, V. V. ; KAMANTSEV, A. P. ; SHAVROV, V. G. ; MASHIROV, A. V. ; GOMES, A. M. ; TAKEUCHI, A. Y. ; de Lima, O. F. ; ARAÚJO-MOREIRA, F. M. . Deciphering M - T diagram of shape memory Heusler alloys: reentrance, plateau and beyond. PHILOSOPHICAL MAGAZINE LETTERS , v. 96, p. 1-8, 2016.

• SERGEENKOV, S. ; BRISCESE, F. ; GRETHER, M. ; DE LLANO, M. . Origin of a nonlinear contribution to the shift of the critical temperature in atomic Bose-Einstein condensates. JETP Letters , v. 101, p. 376-379, 2015.

• SERGEENKOV, S. ; Cichetto, L. ; LONGO, E. ; Araujo-Moreira, F. M. . Evidence for resonant scattering of electrons by spin fluctuations in LaNiO3/LaAlO3 heterostructures grown by pulsed laser deposition. JETP Letters , v. 102, p. 383-386, 2015.

• Sergeenkov, S ; CICHETTO, L ; ZAMPIERI, M ; LONGO, E ; Araújo-Moreira, F M . Scaling like behaviour of resistivity observed in LaNiO thin films grown on SrTiO substrate by pulsed laser deposition. Journal of Physics. Condensed Matter (Print) , v. 27, p. 485307, 2015.

• SERGEENKOV, SERGE ; AUSLOOS, MARCEL . Manifestation of interdot spin tunneling effects in ordered arrays of quantum dots: an anomalous magnetization of. Philosophical Magazine Letters (Print) , v. 95, p. 534-538, 2015.

• SERGEENKOV, S. ; Araujo-Moreira, F.M. . Thermomagnetic effect in a twisted carbon nanotube. Solid State Communications , v. 158, p. 58-60, 2013.

• SERGEENKOV, S. ; Araujo-Moreira, F. M. . Analog of fishtail anomaly in plastically deformed graphene. JETP Letters , v. 98, p. 88-90, 2013.

• SERGEENKOV, S. ; Araujo-Moreira, F.M. . On converse magnetoelectric effect in a twisted carbon nanotube under the influence of applied magnetic field. Physics Letters. A (Print) , v. 377, p. 3158-3160, 2013.

• Souza, N.S. ; Rodrigues, A.D. ; Cardoso, C.A. ; Pardo, H. ; Faccio, R. ; Mombru, A.W. ; Galzerani, J.C. ; de Lima, O.F. ; SERGEENKOV, S. ; Araujo-Moreira, F.M. . Physical properties of nanofluid suspension of ferromagnetic graphite with high Zeta potential. Physics Letters. A (Print) , v. 376, p. 544-546, 2012.

• STARI, C. ; Cichetto, L. ; Peres, C.H.M.A. ; Rivera, V.A.G. ; SERGEENKOV, S. ; Cardoso, C.A. ; MAREGA, E. ; Araújo-Moreira, F.M. . Comparative study on structure and magnetic properties of polycrystalline PrxY1 xBa2Cu3O7 prepared in oxygen and argon atmosphere. Journal of Alloys and Compounds , v. 528, p. 135-140, 2012.

• SERGEENKOV, S. ; SANCHES, E. ; SALLA, R.V.F ; Rivera, V. A. G. ; Cichetto, L. ; ARAUJO-MOREIRA, F. . Analog of the susceptibility spectrum for levitation forces between a superconductor and a permanent magnet. Journal of Applied Physics , v. 112, p. 033908-5, 2012.

• NASCIMENTO, F.M. ; SERGEENKOV, S. ; Araújo-Moreira, F M . Reconstructing 3D profiles of flux distribution in array of unshunted Josephson junctions from 2D scanning SQUID microscope images. Physics Letters. A (Print) , v. 376, p. 2722-2724, 2012.

• Souza, N. S. ; SERGEENKOV, S. ; Rodrigues, A. D. ; Cardoso, C. A. ; Pardo, H. ; Faccio, R. ; MOMBRÚ, A. W. ; GALZERANI, J. C. ; de Lima, O. F. ; ARAÚJO-MOREIRA, F. M. . Stability Issues and Structure-Sensitive Magnetic Properties of Nanofluid Ferromagnetic Graphite. Journal of Nanofluids , v. 1, p. 143-147, 2012.

• SERGEENKOV, SERGEI . Towards weakening of the Coulomb blockade in artificially prepared clusters of superconducting grains. AIP Advances , v. 1, p. 022122-3, 2011.

• SERGEENKOV, S. ; Rivera, V.A.G. ; MAREGA, E. ; Araujo-Moreira, F.M . Field induced Kosterlitz-Thouless transition in two-dimensional array of Nb???AlOx???Nb Josephson junctions. Solid State Communications , p. 892-894, 2011.

• SERGEENKOV, S. ; Cardoso, C. A. ; Andreeta, M. R. B. ; Hernandes, A. C. ; Leite, E. R. ; Moreira, F. M. Araújo- . Growth and magnetic properties of bulk electron doped La0.7Ce0.3MnO3 manganites. Physica Status Solidi. A, Applications and Materials Science (Print) , v. 208, p. 1704-1707, 2011.

• SERGEENKOV, S. ; Araujo-Moreira, F. M. . On the field-induced diaelastic effect in a small Josephson contact. JETP Letters , v. 94, p. 845-848, 2011.

• SERGEENKOV, S. ; Moraes, F. ; Furtado, C. ; Araujo-Moreira, F.M. . Influence of electron phonon interaction on soliton mediated spin charge conversion effects in two-component polymer model. Annals of Physics (Print) , v. 325, p. 455-464, 2010.

• SERGEENKOV, S. ; Cichetto, L. ; Rivera, V. A. G. ; STARI, C. ; MAREGA, E. ; Cardoso, C. A. ; Araujo-Moreira, F. M. . Pinning of spiral fluxons by giant screw dislocations in YBa2Cu3O7 ? ? single crystals: Josephson analog of the fishtail effect. JETP Letters , v. 91, p. 30-34, 2010.

• SERGEENKOV, S. ; Rivera, V. A. G. ; MAREGA, E. ; Araujo-Moreira, F. M. . Universal resistance capacitance crossover in current-voltage characteristics for unshunted array of overdamped Nb AlO[sub x] Nb Josephson junctions. Journal of Applied Physics , v. 107, p. 096102-3, 2010.

• Rivera, V.A.G. ; SERGEENKOV, S. ; MAREGA, E. ; Araújo-Moreira, F.M. . Manifestation of geometric resonance in current dependence of AC susceptibility for unshunted array of Nb Alx Nb Josephson junctions. Physica. C, Superconductivity (Print) , p. 1946-1948, 2010.

• SERGEENKOV, SERGEI ; ROTOLI, G. . Wireless connection between Josephson qubits. Physical Review A (Online) , v. 79, p. 044301-4, 2009.

• Rivera, V. A. G. ; SERGEENKOV, S. ; STARI, C. ; Cichetto, L. ; Cardoso, C. A. ; MAREGA, E. ; Araujo-Moreira, F. M. . Unusually strong coherent response from grain-boundary Josephson network in polycrystalline Pr x Y1 ? x Ba2Cu3O7 ? ?. JETP Letters , v. 90, p. 365-369, 2009.

• Rivera, V.A.G. ; SERGEENKOV, S. ; MAREGA, E. ; Araújo-Moreira, F.M. . Manifestation of ?-contacts in magnetic field dependence of I VI V characteristics for proximity-type 2D Josephson junction array. Physics Letters. A (Print) , v. 374, p. 376-379, 2009.

• Souza, N. S. ; SERGEENKOV, S. ; Speglich, C. ; Rivera, V. A. G. ; Cardoso, C. A. ; Pardo, H. ; Mombru?, A. W. ; Rodrigues, A. D. ; de Lima, O. F. ; Arau?jo-Moreira, F. M. . Synthesis, characterization, and magnetic properties of room-temperature nanofluid ferromagnetic graphite. Applied Physics Letters , v. 95, p. 233120, 2009.

• SERGEENKOV, S. ; Souza, N. S. ; Speglich, C. ; Rivera, V. A. G. ; Cardoso, C. A. ; Pardo, H. ; Mombru?, A. W. ; Araújo-Moreira, F.M. . Manifestation of finite temperature size effects in nanogranular magnetic graphite. Journal of Applied Physics , v. 106, p. 116101, 2009.

• Sergeenkov, S ; Souza, N S ; Speglich, C ; Rivera, V A G ; Cardoso, C A ; Pardo, H ; Mombrú, A W ; Araújo-Moreira, F M . Temperature oscillations of magnetization observed in nanofluid ferromagnetic graphite. Journal of Physics. Condensed Matter , v. 21, p. 495303, 2009.

• Bakke, K. ; Furtado, C. ; SERGEENKOV, S. . Holonomic quantum computation associated with a defect structure of conical graphene. Europhysics Letters (Print) , v. 87, p. 30002, 2009.

• ARAUJO-MOREIRA, F. ; SERGEENKOV, SERGEI . Dynamical reentrance and geometry imposed quantization effects in Nb?AlOx?Nb Josephson junction arrays. Superconductor Science and Technology , v. 21, p. 045002-16, 2008.

• ROTOLI, G. ; SERGEENKOV, S. ; FILATRELLA, G. ; ARAUJO-MOREIRA, F. . Thermal expansion of granular superconductors based on elastic response of Josephson junction arrays. Journal of Physics. Conference Series (Online) , v. 97, p. 012235-6, 2008.

• SERGEENKOV, SERGEI . Novel magnetoinductance effects in Josephson junction arrays: A single-plaquette approximation. Physics Letters A , v. 372, p. 2917-2919, 2008.

• V.A.G. Rivera ; STARI, C. ; SERGEENKOV, S. ; MAREGA, E. ; ARAUJO-MOREIRA, F. . Manifestation of vortex depinning transition in nonlinear current?voltage characteristics of polycrystalline superconductor Y{1-x}Pr{x}Ba{2}Cu{3}O{7}. Physics Letters A , v. 372, p. 5089-5092, 2008.

• SERGEENKOV, S. ; ROTOLI, G. ; FILATRELLA, G. ; ARAUJO-MOREIRA, F. . Thermal expansion of Josephson junctions as an elastic response to an effective stress field. Physical Review B - Condensed Matter and Materials Physics , v. 75, p. 014506-6, 2007.

• SERGEENKOV, S. ; LANFREDI, AJC ; ARAUJO-MOREIRA, F. . Possible manifestation of spin fluctuations in the temperature behavior of resistivity in Sm_{1.85}Ce_{0.15}CuO_4 thin films. JETP Letters , v. 85, p. 592-594, 2007.

• SERGEENKOV, SERGEI . Influence of chemical pressure effects on nonlinear thermal conductivity of intrinsically granular superconductors. Journal of Applied Physics , v. 102, p. 066104-3, 2007.

• SERGEENKOV, S. ; MUCHA, J. ; PEKALA, M. ; DROZD, V. ; AUSLOOS, M. . Influence of Zeeman splitting and thermally excited polaron states on magneto-electrical and magneto-thermal properties of magnetoresistive polycrystalline manganite La_{0.8}Sr_{0.2}MnO_3. Journal of Applied Physics , v. 102, p. 083916-9, 2007.

• OSSANDON, J. ; GIORDANO, J. ; ESQUINAZI, P. ; KEMPA, H. ; SERGEENKOV, S. . Non-linear response of AC conductivity in narrow strips of YBCO thin films near T_C. Journal of Physics. Conference Series , v. 43, n.Aceito, p. 655-658, 2006.

• LANFREDI, AJC ; SERGEENKOV, S. ; ARAUJO-MOREIRA, F. . Probing pairing symmetry of Sm_{1.85}Ce_{0.15}CuO_4 via conductance-voltage measurements: Evidence for strong impurity scattering. Physics Letters A , v. 359, p. 696-699, 2006.

• SERGEENKOV, S. ; ARAUJO-MOREIRA, F. . On the origin of unusual transport properties observed in densely packed polycrystalline CaAl_2. Journal of Applied Physics , v. 100, p. 096101-2, 2006.

• LANFREDI, AJC ; SERGEENKOV, S. ; ARAUJO-MOREIRA, F. . Influence of structural disorder on low-temperature behavior of penetration depth in electron-doped high-T_C thin films. Physica. C, Superconductivity , v. 450, p. 40-44, 2006.

• SERGEENKOV, S. ; LANFREDI, AJC ; ARAUJO-MOREIRA, F. . Irreversibility line and low-field grain-boundary pinning in electron-doped superconducting thin films. Journal of Applied Physics , v. 100, p. 123903-4, 2006.

• ARAUJO-MOREIRA, F. ; MALUF, W. ; SERGEENKOV, S. . On the origin of reentrance in 2D Josephson Junction Arrays. European Physical Journal B , v. 44, n.1, p. 33-39, 2005.

• OSSANDON, J. ; SERGEENKOV, S. ; ESQUINAZI, P. ; KEMPA, H. . Higher harmonics of ac voltage response in narrow strips of YBa_2Cu_3O_7 thin films. Superconductor Science and Technology , v. 18, n.3, p. 325-329, 2005.

• SERGEENKOV, S. . Magnetic field induced polarization effects in intrinsically granular superconductors. Journal of Experimental and Theoretical Physics , v. 101, n.5, p. 919-925, 2005.

• STARI, C. ; MORENO-GOBBI, A. ; MOMBRU, A. ; SERGEENKOV, S. ; LANFREDI, AJC ; CARDOSO, C. ; ARAUJO-MOREIRA, F. . Elastic properties of polycrystalline YBa_2Cu_3O_7: Evidence for granularity induced martensitic behavior. Physica. C, Superconductivity , v. 433, n.1-2, p. 50-58, 2005.

• SERGEENKOV, S. ; ARAUJO-MOREIRA, F. . Manifestation of geometric quantization effects in temperature behavior of AC magnetic response of Josephson Junction Arrays. JETP Letters , v. 80, n.9, p. 580-583, 2004.

• ARAUJO-MOREIRA, F. ; MALUF, W. ; SERGEENKOV, S. . Influence of nonuniform critical current density profile on magnetic field behavior of AC susceptibility in 2D Josephson Junction Arrays. Solid State Communications , v. 131, p. 759-762, 2004.

• SERGEENKOV, S. . Chemomagnetism, magnetoconcentration effect and fishtail anomaly in chemically induced granular superconductors. JETP Letters , v. 77, n.2, p. 94-98, 2003.

• SERGEENKOV, S. . Electric field dependence of thermal conductivity of a granular superconductor: Giant field-induced effects predicted. JETP Letters , v. 76, n.3, p. 170-174, 2002.

• SERGEENKOV, S. . Deformation-induced thermomagnetic effects in a twisted weak-link-bearing superconductor. JETP Letters , v. 75, n.7, p. 317-321, 2002.

• SERGEENKOV, S. ; PASSOS, W. ; LISBOA-FILHO, P. ; ORTIZ, W. . Universal temperature behavior of remanent magnetization observed in low-T_c and high-T_c Josephson Junction Arrays. Physics Letters A , v. 291, n.4-5, p. 311-314, 2001.

• PASSOS, W. ; LISBOA-FILHO, P. ; CAPARROZ, R. ; ARAUJO-MOREIRA, F. ; SERGEENKOV, S. ; ORTIZ, W. . Granularity in superconductors: intrinsic properties and processing-dependent effects. Physica. C, Superconductivity , v. 354, n.1-4, p. 189-196, 2001.

• SERGEENKOV, S. ; AUSLOOS, M. ; BOUGRINE, H. ; CLOOTS, R. . Anomalous temperature behavior of resistivity in lightly doped manganites around a metal-insulator phase transition. JETP Letters , v. 70, n.7, p. 481-487, 1999.

• SERGEENKOV, S. ; BOUGRINE, H. ; AUSLOOS, M. ; GILABERT, A. . Negative magnetoresistance in a mixed-valence La_{0.6}Y_{0.1}Ca_{0.3}MnO_3: Evidence for charge delocalization governed by the Curie-Weiss law. JETP Letters , v. 70, n.2, p. 141-146, 1999.

• SERGEENKOV, S. . Piezomagnetism and stress induced paramagnetic Meissner effect in mechanically loaded high-T_c granular superconductors. JETP Letters , v. 70, n.1, p. 36-41, 1999.

• SERGEENKOV, S. ; BOUGRINE, H. ; AUSLOOS, M. ; GILABERT, A. . Estimation of the charge carrier localization length from Gaussian fluctuations in the magneto-thermopower of La_{0.6}Y_{0.1}Ca_{0.3}MnO_3. Physical Review B - Condensed Matter and Materials Physics , v. 60, n.17, p. 12322-12328, 1999.

• SERGEENKOV, S. ; AUSLOOS, M. . Phase dependent differential thermopower of SND junctions: Pair-breaking effects and Gaussian fluctuations. Physical Review B - Condensed Matter and Materials Physics , v. 59, n.18, p. 11974-11981, 1999.

• SERGEENKOV, S. ; BOUGRINE, H. ; AUSLOOS, M. ; CLOOTS, R. . A sharp decrease of resistivity in La_{0.7}Ca_{0.3}Mn_{0.96}Cu_{0.04}O_3: Evidence for Cu assisted coherent tunneling of spin polarons. JETP Letters , v. 69, n.11, p. 858-862, 1999.

• SERGEENKOV, S. ; AUSLOOS, M. . Probing the field-induced variation of the chemical potential in Bi_2Sr_2CaCu_2O_y via the magneto-thermopower measurements. Journal of Experimental and Theoretical Physics , v. 89, n.1, p. 140-143, 1999.

• SERGEENKOV, S. ; JOSE, J. . Analog of magnetoelectric effect in high-T_c granular superconductors. Europhysics Letters , v. 43, n.4, p. 469-475, 1998.

• SERGEENKOV, S. . Nonlinear Seebeck effect in a model granular superconductor. JETP Letters , v. 67, n.9, p. 680-684, 1998.

• SERGEENKOV, S. . On piezophase effects in mechanically loaded atomic scale Josephson junctions. Journal of Physics. Condensed Matter , v. 10, n.16, p. L265-L268, 1998.

• SERGEENKOV, S. . On electrostriction of a granular superconductor. Solid State Communications , v. 106, n.7, p. 451-454, 1998.

• SERGEENKOV, S. . Magnetic field induced charging effects in Josephson Junction Arrays. The European Physical Journal. B, Condensed Matter Physics , v. 7, n.10, p. 1175-1179, 1997.

• SERGEENKOV, S. . Dipole-dipole interaction of Josephson diamagnetic moments. Physics Letters A , v. 225, n.1-3, p. 167-169, 1997.

• SERGEENKOV, S. ; GRIDIN, V. ; AUSLOOS, M. . Influence of a non-uniform current density profile on quasiparticle excitations and thermally activated flux creep in YBa_2Cu_3O_{7-\delta}. Zeitschrift für Physik. B, Condensed Matter , v. 101, n.4, p. 565-571, 1996.

• HOUSSA, M. ; AUSLOOS, M. ; SERGEENKOV, S. . Electronic contribution to the thermal conductivity of layered high-T_c materials. Journal of Physics. Condensed Matter , v. 8, n.12, p. 2043-2052, 1996.

• GRIDIN, V. ; SERGEENKOV, S. ; AUSLOOS, M. . Quasi-particle versus vortex motion dissipation in the mixed state of YBa_2Cu_3O_7. Solid State Communications , v. 98, n.7, p. 623-627, 1996.

• SERGEENKOV, S. ; AUSLOOS, M. . Dislocation induced AC Josephson effect in high-T_c superconductors. Physics Letters A , v. 206, n.5-6, p. 383-385, 1995.

• SERGEENKOV, S. ; AUSLOOS, M. . Thermal conductivity of type II superconductors in the mixed state. Physical Review B - Condensed Matter and Materials Physics , v. 52, n.5, p. 3614-3618, 1995.

• SERGEENKOV, S. . Pinning via intrinsic weak links: a possible scenario and applications. Journal of Applied Physics , v. 78, n.2, p. 1114-1122, 1995.

• SERGEENKOV, S. . Electric field induced converse piezoeffect in screw dislocated YBa_2Cu_3O_7. Journal of Applied Physics , v. 77, n.9, p. 4831-4833, 1995.

• SERGEENKOV, S. . Ergodic versus nonergodic behavior in oxygen deficient high-T_c superconductors. Physical Review B - Condensed Matter and Materials Physics , v. 51, n.2, p. 1223-1228, 1995.

• SERGEENKOV, S. ; AUSLOOS, M. . Field induced aging effects in inhomogeneous superconductors. Physical Review B - Condensed Matter and Materials Physics , v. 52, n.18, p. 13619-13624, 1995.

• GRIDIN, V. ; SERGEENKOV, S. ; STRYDOM, A. ; PLESSIS, P. V. . Large low temperature magnetoresistance in CeCu_2Sn_2 and CeNi_2Sn_2. Physical Review B - Condensed Matter and Materials Physics , v. 50, n.17, p. 12995-12998, 1994.

• BOUGRINE, H. ; SERGEENKOV, S. ; AUSLOOS, M. ; CLOOTS, R. ; GRIDIN, V. . Nonequilibrium effects in the thermal conductivity of Bi_2Sr_2CaCu_2O_x. Solid State Communications , v. 91, n.7, p. 571-575, 1994.

• SERGEENKOV, S. ; AUSLOOS, M. ; MEHBOD, M. . On back bending of the Hall number density in YBCO. Journal of Physics. Condensed Matter , v. 6, n.27, p. L373-L377, 1994.

• SERGEENKOV, S. ; GRIDIN, V. . Tunable atomic scale Josephson effect in dislocated superconductors. Physical Review B - Condensed Matter and Materials Physics , v. 50, n.2, p. 1293-1296, 1994.

• SERGEENKOV, S. ; GRIDIN, V. ; VILLIERS, P. ; AUSLOOS, M. . Estimation of effective electronic mass from gaussian fluctuations of the magneto-thermopower of the polycrystalline Bi_2Sr_2CaCu_2O_x. Physica Scripta. Topical Issues , v. 49, p. 637-640, 1994.

• SERGEENKOV, S. ; AUSLOOS, M. ; CLOOTS, R. ; HANNAY, C. ; GODELAINE, P. . London-Silsbee state in magnetically textured DyBa_2Cu_3O_7. Europhysics Letters , v. 24, n.5, p. 397-402, 1993.

• SERGEENKOV, S. ; AUSLOOS, M. ; BOUGRINE, H. ; CLOOTS, R. ; GRIDIN, V. . Thermoelectric power of textured Bi_2Sr_2CaCu_2O_8: Evidence for field-induced hysteretic behavior. Physical Review B - Condensed Matter and Materials Physics , v. 48, n.22, p. 16680-16689, 1993.

• SENGUPTA, S. ; SHI, D. ; SERGEENKOV, S. ; MCGINN, P. . Nonlinear U(j) law from magnetic relaxation in Bi_2Sr_2CaCu_2O_x single crystals: Flux motion through double-kink formation of pancake vortices. Physical Review B - Condensed Matter and Materials Physics , v. 48, n.9, p. 6736-6739, 1993.

• SERGEENKOV, S. ; AUSLOOS, M. . On thermal conductivity of a granular superconductor. Physical Review B - Condensed Matter and Materials Physics , v. 48, n.6, p. 4188-4191, 1993.

• SERGEENKOV, S. ; AUSLOOS, M. . On magnetostriction of a granular superconductor. Physical Review B - Condensed Matter and Materials Physics , v. 48, n.1, p. 604-606, 1993.

• MEHBOD, M. ; SERGEENKOV, S. ; AUSLOOS, M. . AC susceptibility in YBa_2(Cu_{1-x}Fe_x)_3O_7: Evidence for two-step IL crossover. Physical Review B - Condensed Matter and Materials Physics , v. 48, n.1, p. 483-486, 1993.

• GRIDIN, V. ; SERGEENKOV, S. ; VILLIERS, P. ; AUSLOOS, M. . Carrier type dependent thermoelectric response of the SNS configuration in a C-shaped polycrystalline Bi_2Pb_2Sr_2CaCu_3O_y. Physical Review B - Condensed Matter and Materials Physics , v. 47, n.21, p. 14591-14594, 1993.

• SERGEENKOV, S. ; AUSLOOS, M. . Thermoelectric power of inhomogeneous superconductors. Physical Review B - Condensed Matter and Materials Physics , v. 47, n.21, p. 14476-14480, 1993.

• BOUGRINE, H. ; SERGEENKOV, S. ; AUSLOOS, M. ; MEHBOD, M. . Thermal conductivity of twinned YBa_2Cu_3O_7 and tweeded YBa_2(Cu_{1-x}Fe_x)_3O_7 in a magnetic field: Evidence for intrinsic proximity effect. Solid State Communications , v. 86, n.8, p. 513-516, 1993.

• SERGEENKOV, S. . On the optimum silver content in silver-doped high-T_c superconductors. IEEE Transactions on Applied Superconductivity , v. 3, n.1, p. 1168-1169, 1993.

• SERGEENKOV, S. . On weak-link behavior of silver-doped high-T_c granular superconductors. Physica. C, Superconductivity , v. 205, n.1&2, p. 1-13, 1993.

• AKSENOV, V. ; DOKUKIN, E. ; NIKITENKO, Y. ; SERGEENKOV, S. . Neutron polarization investigations in high-T_c superconductors. Physica Scripta. Topical Issues , v. T49, p. 650-655, 1993.

• SERGEENKOV, S. ; AUSLOOS, M. . On magnetic field dependence of ultrasonic attenuation in a granular superconductor. Physical Review B - Condensed Matter and Materials Physics , v. 46, n.21, p. 14223-14225, 1992.

• SERGEENKOV, S. . On dislocation-induced reentrant-like behavior in deoxygenated superconductors. Journal of Superconductivity , v. 4, p. 431-435, 1991.

• SERGEENKOV, S. . Anomalous magnetic properties of weak-link-bearing high-T_c superconductors. Physica. C, Superconductivity , v. 185, p. 1527-1528, 1991.

• SERGEENKOV, S. . On field-induced irreversibility line crossover in deoxygenated weak-link-containing high-T_c superconductors. Solid State Communications , v. 79, n.10, p. 863-866, 1991.

• SERGEENKOV, S. . Memory effects in high-T_c superconductive glass model. Physica. C, Superconductivity , v. 174, n.1-3, p. 195-198, 1991.

• SERGEENKOV, S. . On excess magnetoconductivity of a superconductive glass. Zeitschrift für Physik. B, Condensed Matter , v. 82, p. 325-327, 1991.

• SERGEENKOV, S. . On fluctuation-induced diamagnetism of a superconductive glass. Physica. C, Superconductivity , v. 171, n.5&6, p. 438-440, 1990.

• SERGEENKOV, S. . Thermoelectric effects in superconductors: the role of weak links. Journal of Superconductivity , v. 3, n.4, p. 417-418, 1990.

• SERGEENKOV, S. . On logarithmic current-voltages of the superconductive glass model. Physica Status Solidi. B, Basic Research , v. 160, p. K137-K140, 1990.

• SERGEENKOV, S. . Nonlinear current-voltage characteristics and critical current of the superconductive glass model. Physica. C, Superconductivity , v. 167, n.3&4, p. 339-342, 1990.

• AKSENOV, V. ; KORNILOV, E. ; SERGEENKOV, S. . Dipole superconductive glass model in Josephson medium. Physica. C, Superconductivity , v. 162, p. 229-230, 1989.

• SERGEENKOV, S. . Diamagnetic correlations of the superconductive glass model. Physica. C, Superconductivity , v. 159, n.1&2, p. 43-45, 1989.

• AKSENOV, V. ; SERGEENKOV, S. . Nonequilibrium behavior and nonergodicity of superconductive glass model. Physica. C, Superconductivity , v. 156, n.2, p. 235-242, 1988.

• AKSENOV, V. ; SERGEENKOV, S. . On the phase diagram of the high-T_c superconductive glass model. Physica. C, Superconductivity , v. 156, n.1, p. 18-23, 1988.

• AKSENOV, V. ; SERGEENKOV, S. . Scaling behavior of the relaxation function in a proton glass model. Ferroelectrics Letters Section , v. 9, p. 1-5, 1988.

• PASHAEV, O. ; SERGEENKOV, S. . Nonlinear sigma -models with noncompact symmetry group in the theory of a nearly ideal Bose gas. Physica. A , v. 137, n.1-2, p. 282-294, 1986.

• SERGEENKOV, S. . Kink-like solution in U(1,1) symmetry Bose-condensate. Physics Letters A , v. 100, n.9, p. 474-476, 1984.

• MAKHANKOV, V. ; PASHAEV, O. ; SERGEENKOV, S. . Hole-like excitations in many component systems. Physica Scripta. Topical Issues , v. 29, p. 521-525, 1984.

• MAKHANKOV, V. ; PASHAEV, O. ; SERGEENKOV, S. . Colored solitons in stable medium. Physics Letters A , v. 98, n.5-6, p. 227-232, 1983.

• SERGEENKOV, SERGEI . New Developments in Josephson Junctions Research. Kerala: Transworld Research Network, 2010. 139p .

• CARDOSO, C. ; SERGEENKOV, S. ; Andreeta, M. R. B. ; HERNANDES, A.C. ; Leite, E. R. ; de Lima, O.F. ; ARAÚJO-MOREIRA, F. M. . Growth, Characterization and Magnetic Properties of Polycrystalline Fibers of Electron Doped Manganites. In: Lixin Yu. (Org.). Doping: Properties, Mechanisms and Applications. 1ed.New York: Nova Science, 2013, v. , p. 71-80.

• ARAUJO-MOREIRA, F. ; SERGEENKOV, S. . Experimental and Theoretical Study on 2D Ordered and 3D Disordered SIS-type Arrays of Josephson Junctions. In: Sergei Sergeenkov. (Org.). New Developments in Josephson Junctions Research. Kerala: Transworld Research Network, 2010, v. , p. 25-44.

• Sergeenkov, S . 2D Arrays of Josephson Nanocontacts and Nanogranular Superconductors. In: A. V. Narlikar; Y.Y. Fu. (Org.). Oxford Handbook of Nanoscience and Technology. Oxford: Oxford University Press, 2010, v. 1, p. 703-731.

• ARAUJO-MOREIRA, F. ; SERGEENKOV, SERGEI . Magnetic Properties of Artificially Prepared Highly Ordered Two-Dimensional Shunted and Unshunted Nb-AlOx-Nb Josephson Junctions Arrays. In: James R. Tobin. (Org.). Superconductivity Research Developments. Nova Science, New York: , 2008, v. , p. 27-62.

• SERGEENKOV, S. ; LANFREDI, AJC ; ARAUJO-MOREIRA, F. . Magnetic and Transport Properties of Electron-doped Superconducting Thin Films. In: Arnold H. Burness. (Org.). Superconducting Thin Films: New Research. New York: Nova Science, 2008, v. , p. 122-149.

• SERGEENKOV, S. . Chemically Induced Nanoscale Josephson Effects in Non-Stoichiometric High-Temperature Superconductors. In: A. Narlikar. (Org.). Studies of High Temperature Superconductors. Nova Science, New York: , 2006, v. 50, p. 90-105.

• SERGEENKOV, S. . On critical current enhancement in dislocated, deoxygenated and irradiated superconductors: a unified approach. In: R.W. Stevens. (Org.). New Developments in Superconductivity Research. Nova Science, New York: , 2004, v. , p. 101-129.

• SERGEENKOV, S. . Novel effects in high-T_c granular superconductors. In: A. Narlikar. (Org.). Studies of High Temperature Superconductors. Nova Science, New York: , 2001, v. 39, p. 117-131.

• SERGEENKOV, S. . Probing mixed pairing state via thermoelectric response of SND junctions. In: NATO Advanced Research Workshop on Symmetry and Pairing in Superconductors, 1999, Yalta, Crimea. NATO Science Partnership Series (Sub-Series: High Technology). Dordrecht: Kluwer Academic Publishers, 1998. v. 63. p. 91-99.

• SERGEENKOV, S. . Flicker-noise spectrum in weak-link-containing superconductors. In: IV International Conference on Superconducting Quantum Effect Devices and their Applications (SQUID'91), 1992, Berlin, Germany. Springer Proceedings in Physics. Berlin: Springer Verlag, 1991. v. 64. p. 57-60.

• SERGEENKOV, S. . Glassy behavior of deoxygenated high-T_c superconductors. In: NATO Advanced Study Institute on Physics and Materials Science of High-T_c Superconductors-II, 1992, Porto Carras, Greece. NATO Advanced Study Institute Series (Series E: Applied Sciences). Dordrecht: Kluwer Academic Publishers, 1991. v. 209. p. 125-138.

• SERGEENKOV, S. . On nonlinear current-voltages of high-T_c superconductive glass. In: XXVI Winter School of Theoretical Physics, 1990, Karpacz, Poland. Ordering Phenomena in Condensed Matter Physics. Singapore: World Scientific, 1990. p. 233-238.

• AKSENOV, V. ; SERGEENKOV, S.A. . Phase diagram of superconducting glass. In: International Conference on Materials Science for High Technologies (MASHTEC '90), 1990, Dresden. Materials Science Forum, 1990. v. 62. p. 201-204.

• MAKHANKOV, V. ; PASHAEV, O. ; SERGEENKOV, S. . Bose-gas models with noncompact symmetry groups. In: III International Symposium on Selected Topics in Statistical Mechanics, 1984, Dubna, Russia. Proceedings. Dubna: D17-84-850, JINR Publishing Department, 1984. v. II. p. 45-52.

• Souza, N. S. ; SERGEENKOV, SERGEI ; Rodrigues, A. D. ; Cardoso, C A ; Pardo, H ; Faccio, R. ; MOMBRÚ, A. W. ; GALZERANI, J. C. ; ARAÚJO-MOREIRA, F. M. . Physical Properties and Stability Issues of Nanofluid Ferromagnetic Graphite. In: XXXVII Encontro Nacional de Física da Matéria Condensada, 2014, Costa do Sauipe, BA. XXXVII Encontro Nacional de Física da Matéria Condensada. Sao Paulo: SBF, 2014.

• V.A.G. Rivera ; ARAUJO-MOREIRA, F. ; STARI, C ; SERGEENKOV, S. ; MAREGA, E. . Manifestation of vortex depinning transition in nonlinear current-voltage characteristics of Y_{1-x}Pr_{x}Ba_2Cu_3O_7. In: Encontro Nacional de Física da Matéria Condensada, 2008, Águas de Lindóia, SP. XXXI National Conference on Condensed Matter Physics. São Paulo: Sociedade Brasileira de Física, 2008.

• CARDOSO, C. ; SERGEENKOV, S. ; ARAUJO-MOREIRA, F. ; Leite, E. R. . Growth and magnetic properties of bulk samples of electron doped manganite La_{1-x}Ce_xMnO_3. In: Encontro Nacional de Física da Matéria Condensada, 2007, São Lourenço. Resumos, São Paulo : Sociedade Brasileira de Física, 2007, 2007.

• OSSANDON, J. ; SERGEENKOV, S. ; ESQUINAZI, P. ; KEMPA, H. ; GIORDANO, J. ; SCHAUFUSS, U. . Non-linear response of ac conductivity in narrow YBCO film strips at the superconducting transition. In: European Conference on Applied Superconductivity (EUCAS), 2005, Vienna, Austria. Proceedings, 2005.

• OSSANDON, J. ; SERGEENKOV, S. ; ESQUINAZI, P. ; KEMPA, H. . Higher harmonics of ac voltage response in narrow strips of YBa_2Cu_3O_7 thin films. In: Meeting of The Chilean Physical Society, 2004, Antofagasta, Chile. Proceedings, 2004.

• SERGEENKOV, S. ; ROTOLI, G. . High-T_c Josephson junction systems in magnetic field: Paramagnetism and dynamical effects. In: European Conference on Applied Superconductivity (EUCAS), 2003, Sorrento, Napoli, Italy. Proceedings, 2003.

• SERGEENKOV, S. ; PASSOS, W. ; LISBOA-FILHO, P. ; ORTIZ, W. . Universal temperature behavior of remanent magnetization in conventional and high-T_c granular superconductors. In: V Latin American Workshop on Magnetism and Magnetic Materials, 2001, Bariloche, Argentina. Proceedings, 2001.

• PASSOS, W. ; LISBOA-FILHO, P. ; ARAUJO-MOREIRA, F. ; CAPARROZ, R. ; SERGEENKOV, S. ; ORTIZ, W. . Compiling some anomalies of granular superconductors and recognizing their innate dependence on sample preparation and processing. In: XXIV National Conference on Condensed Matter Physics, 2001, Sao Lourenco. Proceedings, 2001.

• SERGEENKOV, S. ; JOSE, J. . Possible magneto-electric effect in ceramic superconductors. In: 1997 March Meeting of The American Physical Society, 1997, Kansas City, MO, USA. Bulletin of the American Physical Society, 1997. v. 42. p. 121-121.

• SERGEENKOV, S. ; AUSLOOS, M. . Thermal conductivity of composite cuprate ceramics. In: 1997 Fall Meeting of The Materials Research Society, 1997, Boston, MA, USA. Proceedings, 1997.

• SERGEENKOV, S. . On critical current enhancement in dislocated, deoxygenated and irradiated superconductors: A unified approach. In: XX National Conference on Condensed Matter Physics, 1997, Caxambu, MG. Abstracts, 1997.

• SERGEENKOV, S. . Memory and aging effects in high-T_c superconducting ceramics. In: European Conference on Applied Superconductivity, 1991, Birmingham, UK. Abstracts, 1991.

• SERGEENKOV, S. . Magnetic anomalies in tunable atomic scale Josephson junctions. In: International Symposium on Nanostructures and Mesoscopic Systems, 1991, Santa Fe, NM, USA. Proceedings, 1991.

• SERGEENKOV, S. . Diamagnetic correlations of the superconductive glass model. In: International Conference on Strongly Correlated Electron Systems, 1990, Dresden, Germany. Abstracts, 1990.

• SERGEENKOV, S. . Role of granularity in magneto-transport behavior of high-T_c superconductors. In: International Workshop on Electronic Properties of Novel Materials, 1989, Varna, Bulgaria. Abstracts, 1989.

• AKSENOV, V. ; SERGEENKOV, S. ; KORNILOV, E. . Using polarized neutrons to study the vortex structure in high-T_c superconductors. In: International School on Neutron Scattering, 1989, Alushta, Ukraine. Proceedings, 1989.

• AKSENOV, V. ; SERGEENKOV, S. . H-T phase diagram of the high-T_c superconductive glass model. In: XXV All-Union Low Temperature Conference, 1988, Leningrad, USSR. Abstracts, 1988.

• AKSENOV, V. ; SERGEENKOV, S. . Low frequency critical dynamics in a proton glass model. In: All-Union Conference on Solid State Physics, 1987, Kharkov, Ukraine. Abstracts, 1987.

• V.A.G. Rivera ; STARI, C. ; SERGEENKOV, S. ; MAREGA, E. ; ARAUJO-MOREIRA, F. . Revealing the Josephson-Abrikosov vortex states in Y_(1-x)Pr_(x)Ba_(2)Cu_(3)O_(7-d) polycrystalline superconductors. 2008. (Apresentação de Trabalho/Congresso).

• AUSLOOS, M. ; CLOOTS, R. ; PEKALA, M. ; SERGEENKOV, S. . A few aspects of the colossal magnetoresistance of manganites. 2007. (Apresentação de Trabalho/Simpósio).

• ROTOLI, G. ; SERGEENKOV, S. ; FILATRELLA, G. ; ARAUJO-MOREIRA, F. . Thermal expansion of granular superconductors based on elastic response of Josephson junction arrays. 2007. (Apresentação de Trabalho/Congresso).

• AKSENOV, V. ; KORNILOV, E. ; SERGEENKOV, S. . Thermodynamics of dipole superconductive glass model. Dubna: Joint Institute for Nuclear Research, 1989 (JINR Preprint E17-89-514).

• MAKHANKOV, V. ; PASHAEV, O. ; SERGEENKOV, S.A. . Dynamical symmetry and spin waves in isotropic antiferromagnet. Dubna: JINR Publishing Department, 1985 (PEPAN Letters 10, 45).

• BELYAEV, V. ; SERGEENKOV, S. . On the excitation spectrum of dtmu mesic molecule. Dubna: Joint Institute for Nuclear Research, 1983 (JINR Preprint P4-83-734).

• FEDYANIN, V. ; MAKHANKOV, V. ; PASHAEV, O. ; SERGEENKOV, S. . Interaction of solitons in a model of organic charge transfer salts. Dubna: Joint Institute for Nuclear Research, 1983 (JINR Preprint E17-83-755).

• PASHAEV, O. ; SERGEENKOV, S. . Hamiltonian structure of U(p,q) nonlinear Schrodinger equation with nonvanishing boundary conditions. Dubna: Joint Institute for Nuclear Research, 1983 (JINR Preprint P2-83-377).

• MAKHANKOV, V. ; PASHAEV, O. ; SERGEENKOV, S. . Nonlinear Schrodinger equation with nonvanishing boundary conditions: Scalar case. Dubna: Joint Institute for Nuclear Research, 1983 (JINR Preprint P2-83-186).

Outras produções

Projetos de pesquisa

• 2014 - Atual

  Estudo das Propriedades Magnéticas e Plásticas de Grafeno e de Nanotubos de Carbono, Descrição: O principal objetivo da parte teórica será entender, através de cálculos de primeiros princípios, os mecanismos básicos que possam levar a melhor compreensão das propriedades magnéticas, plasticas e de transporte (condutividade eletrica e termal, poder termoelétrico, magnetoresistividade, efeito de Hall, etc) de grafite e de grafeno. Os cálculos de primeiros princípios serão desenvolvidos dentro do contexto da teoria DFT (Teoria do Funcional da Densidade), uma teoria amplamente utilizada e de bastante sucesso no estudo das propriedades eletrônicas e estruturais de materiais diversos, tais como cerâmicas ferroelétricas e nanotubos de carbono, entre muitos outros. Os principais ingredientes de cálculos de primeiros princípios utilizando DFT são: (i) a interação elétron-elétron, tratada através da DFT e (ii) a interação elétron-íon, tratada pelo método dos pseudopotenciais.. , Situação: Em andamento; Natureza: Pesquisa.

• 2011 - 2013

  Estudo Teórico e Experimental das Propriedades Magnéticas e de Transporte de Grafite e Grafeno, Descrição: O presente Projeto visa o desenvolvimento de pesquisa básica e pesquisa aplicada, combinando a realização de experimentos e modelos teóricos no estudo de nanografite magnético e de grafeno. As técnicas experimentais utilizadas incluem medidas de baixas temperaturas até temperatura ambiente utilizando sistemas experimentais para medidas de magnetização, susceptibilidade, resistividade e magnetoresistência. Estas medidas serão realizadas nos laboratorios do Centro Multidisciplinar para o Desenvolvimento de Materias Ceramicos (CMDMC) da UFSCAR.. , Situação: Concluído; Natureza: Pesquisa.

• 2009 - 2010

  Theoretical and Experimental Study on Josephson Junction Arrays: Role of Disorder, Dimensionality and Size Effects, Descrição: Our fruitful collaboration within previous FAPESP projects allowed us to study (both experimentally and theoretically) a number of new interesting phenomena related to the magnetic, transport, elastic and topological properties of artificially prepared highly ordered (periodic) two-dimensional Josephson junction arrays (2D-JJAs) of Nb?AlOx?Nb tunnel junctions as well as their disordered counterparts (3D-JJAs) and granular thin films [1-9]. The latest results on these systems are outlined in our recent review papers [10-13]. It should be mentioned that so far we have always assumed that any effects related to the finiteness of artificially prepared 2D-JJAs, thin films and granular superconductors (3D-JJAs) are small enough and can be safely neglected. However, the recent experimental results and carefully performed theoretical analysis clearly demonstrate [14-17] the importance of finite-size and boundary effects for dynamic properties of JJAs. That is why, in our present FAPESP project we plan to focus our efforts on important interrelations between the dimensionality of the system and its size-dependent effects. The best way to study these effects is by measuring the sample?s current-voltage characteristics (CVC) which is also proved an important tool for investigating the specific dissipation mechanisms in superconducting materials. Besides, as we shall see, this method is also very sensitive to the dimensionality of the sample.. , Situação: Concluído; Natureza: Pesquisa.

• 2009 - 2010

  Properties of room temperature ferromagnetic graphite, Descrição: Recent advances in developing nanographitic systems re-kindled interest in their nontrivial magnetic and transport properties important for numerous applications. Special attention has been paid to the properties mediated by various defect structures (including pores, edges of the planes, chemically induced vacancies, dislocations, tracks produced by particle irradiation, etc) believed to be responsible for room-temperature ferromagnetism based on (super) exchange between localized spins at defect sites. The existence of sufficiently robust ferromagnetic (FM) like magnetization loops has been successfully proved in highly-oriented pyrolytic graphite (HOPG), proton-irradiated graphite, nanographite, graphite containing topographic defects, negative curvature Schwarzite-like carbon nanofoams, fullerene-related carbons, microporous carbon, and carbon nanohorns. At the same time, quite a substantial progress has been made in developing suspended colloids of nano sized magnetic particles, including carbon, graphite and graphene based nanofluids and biocompatible ferrofluids. A specific objective of this project is a comparative study (based on both analytical calculations and numerical simulations) of structural, magnetic and transport (electric, thermal, thermoelectric) properties of nanogranular and nanofluid forms of room-temperature ferromagnetic graphite, which would shed some light on the origin of unusual quantum phenomena in these interesting (and important for applications) materials. , Situação: Concluído; Natureza: Pesquisa.

• 2007 - 2009

  Quantum computers based on Josephson junctions and their arrays, Descrição: A specific objective of our project is to study in much detail those particular properties of JJAs which will be indispensable for their application in feasible quantum computers. To take advantage of the above-discussed latest developments in this field (both experimental and theoretical), a model to be used throughout our study will comprise a mixed combination of 0-loop and -loop arrays of JJs. Special attention will be paid to achieving the optimal performance of JJA-based quantum computer prototype in terms of its speed processing and design (configuration). To this end, we are going to investigate the topological and thermodynamical properties of this model system using (I) our own experience in this field, (II) the modern analytical methods (based on Quantum Field Theory, including Geometric and Gauge Theories of Defects, and temperature Green functions), and (III) the powerful simulation programs (such as Quantum Monte-Carlo algorithm). Through a properly defined minimization procedure for the free energy functional in an applied magnetic field, we expect to find an optimal configuration (topology) of the resulting array. Furthermore, to estimate the influence of external parameters (such as transport currents, electric fields, thermal and chemical potential gradients) and geometric effects (such as finite capacitance and inductance of array) on the performance of JJA based quantum computers, in addition to the tunneling energy EJ, the model under study will include also the Coulomb charging energy EC and total magnetic flux through an array. For speed optimization of a putative quantum computer and its robustness towards abrupt external perturbations, we plan to study the dynamical behavior and non-equilibrium properties of the above-mentioned model by employing both the analytical methods and numerical simulations.. , Situação: Concluído; Natureza: Pesquisa.

• 2006 - 2007

  Theoretical and Experimental Study of Geometry Imposed Quantization Effects in Josephson Junction Arrays, FAPESP, Descrição: Of special interest for us will be study of the numerous thermodynamic properties of our arrays sensitive to their geometry (topology) including measurements of flux governed heat capacity and thermal expansion. Preliminary theoretical analysis based on a single-plaquette approximation shows that both thermal characteristics should exhibit nontrivial (oscillatory) temperature behavior caused by flux lines threading the arrays. Besides, using our expertise in ultrasound technique based measurements, we plan to study peculiarities of the magnetoelastic response of our arrays. It should be stressed that all the above investigations will not only contribute to the fundamental knowledge of such complicated objects as realistic Josephson junction arrays but will be also important for their potential applications in nanotechnology (including spintronics and JJA-based quantum computers).. , Situação: Concluído; Natureza: Pesquisa.

• 2003 - 2003

  Theoretical and Experimental Study of Flux Dynamics in Artificially Prepared Nb-AlO_x-Nb Josephson Junction Arrays, FAPESP, Descrição: (I). By improving resolution of home-made mutual-inductance measurements technique, a pronounced step-like structure (with the number of steps n=4 for all AC fields) has been observed in the temperature dependence of AC susceptibility in artificially prepared two-dimensional Josephson Junction Arrays (2D-JJA) of unshunted Nb-AlO_x-Nb junctions with beta _L(4.2K)=30. Using a single-plaquette approximation of the overdamped 2D-JJA model, we were able to successfully fit our data assuming that steps are related to the geometric properties of the plaquette. The number of steps n corresponds to the number of flux quanta that can be screened by the maximum critical current of the junctions. The steps are predicted to manifest themselves in arrays with the inductance related parameter matching a "quantization" condition beta _L(0)=2\pi (n+1). (II) The magnetic field dependence of complex AC susceptibility of artificially prepared highly ordered (periodic) two-dimensional Josephson junction arrays of unshunted Nb-AlO_x-Nb junctions has been studied experimentally. The observed anomalous behavior can be explained assuming inhomogeneous critical current distribution within a single junction and using single-plaquette approximation of the overdamped 2D-JJA model. (III) A comparative study of the magnetic properties of shunted and unshunted two-dimensional Josephson junction arrays (2D-JJA) is presented. Using a single-plaquette approximation of the 2D-JJA model, we were able to successfully fit all our experimental data (for the temperature, AC and DC field dependencies of susceptibility) and demonstrate that the dynamic reentrance of AC susceptibility is directly linked to the value of the Stewart-McCumber parameter beta _{C}. Based on extensive numerical simulations, a phase diagram beta _{C}-beta _{L} is plotted which demarcates the border between the reentrant and non-reentrant behavior in the arrays.. , Situação: Concluído; Natureza: Pesquisa.

• 2000 - 2000

  Modeling of Magnetic, Thermal and Transport Properties of Ceramics and Granular Superconductors, FAPESP, Descrição: (I) A comparative study of the magnetic remanence exhibited by tridimensional Josephson junction arrays in response to an excitation with an AC magnetic field is presented. The observed temperature behavior of the remanence curves for disordered arrays fabricated from three different materials (Nb, YBa2Cu3O7 and La1.85Sr0.15CuO4) is found to follow the same universal law (based on the explicit temperature expressions for the activation energy and the inductance-dominated contribution to the magnetization of the array within the framework of the phase-slip model) regardless of the origin of the superconducting electrodes of the junctions which form the array. (II) Novel effects are theoretically predicted which should manifest themselves either in weak-links-bearing superconductors or in an artificially prepared Josephson junction arrays (JJAs). In particular, we consider the appearance of an electric-field induced magnetization (analog of the so-called magnetoelectric effect) in a model granular superconductor and the dual effect, that is an appearance of a magnetic field induced electric polarization. Finally, we discuss a possibility of two other interesting effects which are expected to occur in a granular material under mechanical loading. Specifically, we predict the existence of stress induced paramagnetic moment in zero applied magnetic field (Josephson piezomagnetism) and study its influence on a low-field magnetization (leading to a mechanically induced PME).. , Situação: Concluído; Natureza: Pesquisa.

• 1998 - 1999

  Investigation of Colossal Magnetoresistance in Doped Manganites, FNRS, Descrição: (I) To clarify the underlying microscopic transport mechanisms in exhibiting colossal magnetoresistance manganites, the substitution effects on the properties of the most popular La_{0.7}Ca_{0.3}MnO_3 manganites have been studied including the transition element doping at the Mn site. In particular, an anomalous behavior of resistivity in La_{0.7}Ca_{0.3} Mn_{0.96}Cu_{0.04}O_3 due to Cu doping has been found and attributed to the Cu induced weakening of the kinetic carrier's energy and concomitant strengthening of potential barriers (which hamper the charge hopping between neighboring Mn sites). Experimental and theoretical study of Liege-made CMR exhibiting slightly doped manganites via resistivity and magnetoresistivity measurements. (II) At the same time, the colossal negative magnetoresistance observed in La_{0.6}Y_{0.1}Ca_{0.3}MnO_3 at B=1T shows an unusual, nearly perfect symmetry (around the Curie temperature T_C) suggestive of Curie-Weiss dominated transport mechanism in this material both above and below T_C. Attributing this symmetry to strong magnetic fluctuations (which are triggered by the Y substitution and cause a "bootstrap" destruction of the ferromagnetic phase), the data are interpreted in terms of the nonthermal spin hopping and magnetization dependent charge carrier localization length scenario. (III) And finally, the magneto-TEP of La_{0.6}Y_{0.1}Ca_{0.3}MnO_3 was found to exhibit a sharp peak at some temperature T*. We adopt the electron localization scenario and introduce a Ginzburg-Landau type theory which incorporates the two concurrent phase transitions, the paramagnetic-ferromagnetic transition at the Curie point T_C and the "metal-insulator" transition at T_M. As a result, we obtained a simple relationship between T* and the above two critical temperatures (T_C and T_M). The comparison of our data with the model predictions produced reasonable estimate of the charge carrier localization length.. , Situação: Concluído; Natureza: Pesquisa.

• 1998 - 1999

  Study on Symmetry of the Order Parameter in High-T_c Superconductors via Transport Measurements, FNRS, Descrição: (I) Approximating the shape of the magneto-thermoelectric power (TEP) S(T,H) measured in Bi2Sr2CaCu2Oy by an asymmetric linear triangle of the form S(T,H)=Sp(H) ± B±(H)(Tc ? T) with positive B?(H) and B+(H) defined below and above Tc, we observe that B+(H)=2B?(H). To account for this asymmetry, we explicitly introduce the field-dependent chemical potential µ(H) of holes into the Ginzburg?Landau theory and calculate both an average S_av(T,H) and fluctuation contribution S_fl(T,H) to the total magneto-TEP S(T,H). As a result, we find a rather simple relationship between the field-induced variation of the chemical potential in this material and the above-mentioned magneto-TEP data around Tc. (II) We start with revisiting our previous results on thermoelectric response of s-wave-superconductor?normal-metal?s-wave-superconductor (SNS) configuration in a C-shaped BixPb1-xSr2CaCu2Oy sample in order to include strong fluctuation effects. Then, by appropriate generalization of the Ginzburg-Landau theory based on admixture of s-wave (S) and d-wave (D) superconductors, we consider a differential thermoelectric power (TEP) of s-wave-superconductor?normal-metal?d-wave-superconductor (SND) junction. In addition to its strong dependence on the relative phase theta = phi s- phi d between the two superconductors, two major effects are shown to influence the behavior of the predicted TEP. One, based on the chemical imbalance at SD interface, results in a pronounced maximum of the TEP peak near theta = pi /2 (where the so-called s+id mixed pairing state is formed) for two identical superconductors with Tcd=Tcs=Tc. Another effect, which should manifest itself at SD interface comprising an s-wave low-Tc superconductor and a d-wave high-Tc superconductor with Tcd [not equal] Tcs, predicts Sp [is proportional to] Tcd-Tcs for the TEP peak value. The experimental conditions under which the predicted behavior of the induced differential TEP can be measured are discussed.. , Situação: Concluído; Natureza: Pesquisa.

• 1997 - 1997

  Properties of High-T_c Superconductors: Effects of Extrinsic and Intrinsic Granularity, CNPq, Descrição: (I) Zero-temperature field-induced polarization, supercurrent density and the related electrostriction (ES) of a granular superconductor are calculated within a model of 3D Josephson junction arrays. Both the "bulk-modulus-driven ES" (the change of the sample's volume in the free energy upon the applied stress) and the "change-of-phase ES" (due to the stress dependence of the weak-links-induced polarization) are considered. In contrast to magnetostriction of a granular superconductor, its electroelastic behavior is predicted to be dominated by the former contribution for all applied fields. (II) We propose the existence of an electric-field-induced nonlinear magnetization in a weakly coupled granular superconductor due to time-parity violation. As the field increases the induced magnetization passes from para- to dia-magnetic behavior. We discuss conditions under which this effect could be experimentally measured in high-temperature superconductors. (III) A magnetic field induced electric polarization and the corresponding change of an effective junction capacitance are considered within a 3D model of disordered Josephson junction arrays. At some threshold field (near the Josephson network critical field), the effective junction charge and the related capacitance are shown to reach a maximum and to change a sign, respectively. A possibility to observe the predicted effects in artificially prepared arrays of superconducting grains is discussed.. , Situação: Concluído; Natureza: Pesquisa.

• 1996 - 2009

  Granular superconductivity and Josephson junction arrays, Descrição: (i) Within a 2D model of Josephson junction arrays (created by 2D network of twin boundary dislocations with strain fields acting as an insulating barrier between hole-rich domains in underdoped crystals), a few novel effects expected to occur in intrinsically granular material are predicted including: (i) Josephson chemomagnetism (chemically induced magnetic moment in zero applied magnetic field) and its influence on a low-field magnetization (chemically induced paramagnetic Meissner effect), and (ii) magnetoconcentration effect (creation of oxygen vacancies in applied magnetic field) and its influence on a high-field magnetization (chemically induced analog of "fishtail" anomaly). The conditions under which these effects can be experimentally measured in non-stoichiometric high-T_c superconductors are discussed. (II) Two novel phenomena in a granular superconductor under an applied stress are predicted based on piezophase effect (a macroscopic quantum analog of the piezoelectric effect). Namely, we consider the existence of stress induced paramagnetic moment in zero applied magnetic field (piezomagnetism) and its influence on a low-field magnetization (leading to a mechanically induced paramagnetic Meissner effect). The conditions under which these effects can be experimentally measured in high-T_c granular superconductors are discussed. (III) Based upon the above-mentioned mesoscopic quantum effects in Josephson junctions, several novel phenomena in a twisted superconductor (containing a small annular SIS-type contact) under influence of thermal gradient and applied magnetic field are predicted. Namely, we consider a torsional analog of Josephson piezomagnetism (and related magnetomechanical effect) as well as a possible generation of a heat flux induced magnetic moment in a weakly-coupled superconductor under a torsional deformation (analog of Zavaritskii effect) along with the concomitant phenomena.. , Situação: Concluído; Natureza: Pesquisa.

• 1995 - 1995

  Transport Properties of High-T_c Superconductors: Vortices and Weak Links, FNRS, Descrição: Two types of electron scatterers, free (unpinned) vortices and pinned (via extended defects) vortices, are considered and their contribution to the electronic thermal magnetoconductivity of type-II superconductors is discussed. The theoretical predictions are found to be in reasonable agreement with some experimental data on the thermal conductivity of twinned and tweeded high-Tc superconductors in high magnetic fields. A domain theory for aging effects in inhomogeneous superconductors with oxygen-defects-induced intragrain granularity is considered within the superconducting glass model. A qualitative comparison of the model predictions with the observed memory effects in high-Tc single crystals is discussed. We have used the variational approach to calculate the in-plane electronic thermal conductivity of high- T_c superconductors along the lines of a two-fluid model. To account for the layered structure of these compounds, an anisotropic electronic energy spectrum with a Josephson-like coupling between the superconducting planes within a Lawrence - Doniach model has been assumed. Both elastic and inelastic electronic scattering processes are considered. The theoretical results obtained are in quantitative agreement with experimental data on single crystals and polycrystals. These results suggest an electronic origin of the peak observed in the thermal conductivity of these materials. We have studied magnetic relaxation in a single crystal of Bi2Sr2CaCu2Ox and have developed the U-j relationship by an approach we devised earlier. We explain this nonlinear U-j relationship based on the essential modification of the local pinning potential profile associated with flux motion through double-kink formation of the pancake vortices. The important microscopic parameters such as condensation energy, screening length, and vortex core energy have been extracted from the experimental data.. , Situação: Concluído; Natureza: Pesquisa.

• 1993 - 1994

  Low Temperature Behavior of Resistivity and Magnetoresistivity in Ternary Stannides, Descrição: Large negative magnetoresistance of weak Kondo-like systems, CeCu2Sn2 and CeNi2Sn2, was observed in the vicinity of 2 K. At 8.3 T, it reached 7% and 23% for the former and latter materials, respectively. The measurements were taken up to 28 K where the magnetoresistance has diminished even at the highest magnetic fields used in our study. The results were interpreted in terms of relatively weak molecular fields which correlate the spin sublattice of these materials. Following the approach proposed by Abrikosov for calculating resistivity in weakly spin-correlated Kondo-like systems, we were able to fit successfully all our results. The fitting produced an estimate of the spin exchange integral for electron-impurity interaction J, which was found to be of the order of 0.36 meV for both systems.. , Situação: Concluído; Natureza: Pesquisa.

• 1993 - 1994

  Dissipation Mechanisms in High-T_C Superconductors: Vortices vs Quasiparticle Excitations, Descrição: Using a Corbino disk sample geometry we established that the transport current density (flowing radially from the center of the disk to its perimeter) results in a double action on the vortex motion when the applied magnetic field is perpendicular to the disk's plane. First, the depinned vortices are set into a nearly circular motion in the plane of the disk, providing a simple technique to deconvolute the flux motion and the quasiparticle induced components of the total dissipative broadening below Tc. Second, the non-uniform current density profile activates the intrinsic weak links within the material, resulting in proximity dominated quasiparticle contribution. In turn, these intrinsic junctions impede the circular motion of vortices giving rise to the proximity influenced thermally activated flux creep.. , Situação: Concluído; Natureza: Pesquisa.

• 1992 - 1993

  Thermal Conductivity and Thermopower of High-T_c Superconductors: Role of Defects, FNRS, Descrição: (I) The behavior of the thermal conductivity of twinned YBa2Cu3O7 and tweeded YBa2(Cu0.95Fe0.05)3O7 polycrystals in a magnetic field up to 5 T is presented. Data as a function of field are shown to depart from the usual linear behavior of thermal magnetoresistivity (TMR) for conventional superconductors. A set of stretched exponential laws for TMR has been found to describe our data. Such a complex behavior of TMR in the high fiels region is supposed to originate from extended defect mediated intrinsic proximity effect in both samples. The proposed interpretation is based on incorporating two types of phonon scatterers, free (unpinned) and pinned (by the defect cores) vortices, into a conventional picture of phonon-vortex scattering mechanism. (II) The temperature, magnetic-field, and oxygen-deficiency dependence of the thermoelectric power (TEP), S, of an inhomogeneous superconductor with field-induced intragrain granularity is considered via the superconductive-glass model. Below the phase-locking (grain-decoupling) temperature Tg, which defines the coherent properties of a Josephson-junction network, the TEP follows a linear T dependence, while above Tg (but below the single-grain-depairing temperature Tc), S shows a semiconductorlike 1/T behavior. The model predicts the existence of a maximum of S near Tg that increases with the applied magnetic field and changes its sign above some threshold value of the oxygen-deficiency parameter. Attributing the intragrain granularity to clusters of oxygen defects (in the CuO plane), the calculated TEP behavior is found to be in qualitative agreement with the experimentally observed (below Tc) anomalous peak of the magneto-TEP in oxygen-deficient high-Tc superconductors. (III) The ac susceptibilities of YBa2(Cu1-xFex)3O7 polycrystals for 0 <= x<0.05 have been measured as a function of temperature and magnetic-field strength. Two different types of behavior of the irreversibility line, Tm(H), have been found.. , Situação: Concluído; Natureza: Pesquisa.

• 1986 - 1991

  Properties of Superconducting Glasses: Applications to High-T_c Superconductors, Descrição: (I) Nonequilibrium properties of oxide superconductors are investigated in the frame of the 2D XY Josephson glass model. The dependence on temperature and applied magnetic field of the nonergodicity parameter is calculated and shown to have a universal behaviour versus T/Tc (H). In the mode-coupling approximation the critical low-frequency dynamics of the model is studied. The model long-time nonexponential relaxation behaviour of the remanent magnetization is discussed as well. The obtained temperature-field dependences of the magnetization decay rate are in qualitative agreement with the recent experimental data for the lanthanium and yttrium ceramics. (II) The power-law current-voltage characteristic (CVC) V=I^n is calculated via the superconductive glass (SG) model. Temperature and magnetic field dependence of the exponent n(t,H) and the critical current are discussed. It is shown, in particular, that n(Tc,H)=2, thus excluding a possible 2D Kosterlitz-Thouless transition within the SG model. The obtained results are in qualitative agreement with experimental data for high-Tc superconductors. (III) A domain-like theory for aging effects in weak-link-containing systems is presented within the superconductive glass model. The theory allows one to explain, at least qualitatively, the observable memory effects in high-Tc single crystals. (IV) A possible explanation of the experimentally observed field-induced crossover of the irreversibility line in deoxygenated high-Tc superconductors is proposed via a new model of granular superconductor. The model leads to transition from de Almeida-Thouless-like to a Gabay-Toulouse-like laws.. , Situação: Concluído; Natureza: Pesquisa.