George Balster Martins

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Produções bibliográficas

• Almeida, P. A. ; MANYA, M. A. ; FIGUEIRA, M. S. ; ULLOA, S. E. ; ANDA, E. V. ; MARTINS, G. B. . Quantum impurity with 2 3 local moment in one-dimensional quantum wires: A numerical renormalization group study. PHYSICAL REVIEW B , v. 109, p. 045112-045126, 2024.

• Almeida, P. A. ; SOUSA, L. S. ; SCHMIDT, TOME M. ; MARTINS, G. B. . Ferromagnetism in armchair graphene nanoribbon heterostructures. PHYSICAL REVIEW B , v. 105, p. 054416, 2022.

• MANYA, M. A. ; MARTINS, G. B. ; FIGUEIRA, M. S. . Spin-orbit coupling effects on thermoelectric transport properties in quantum dots. Physical Review B , v. 105, p. 165421, 2022.

• G. B. MARTINS ; DINIZ, G. S. ; VERNEK, E. . Band Polarization Effect on the Kondo State in a Zigzag Silicene Nanoribbon. Nanomaterials , v. 12, p. 1480-1492, 2022.

• ALMEIDA, P A ; MARTINS, G B . Thermoelectric transport properties of armchair graphene nanoribbon heterostructures. JOURNAL OF PHYSICS. CONDENSED MATTER (ONLINE) , v. 34, p. 335302, 2022.

• CASSIANO, JOÃO VICTOR VILELA ; MARTINS, GEORGE . Electric-field-generated topological states in a silicene nanotube. JOURNAL OF PHYSICS-CONDENSED MATTER , v. 100, p. 1, 2021.

• DINIZ, G. ; DINIZ, G. S. ; MARTINS, G. B. ; VERNEK, E. . Reentrant Kondo effect for a quantum impurity coupled to a metal-semiconductor hybrid contact. PHYSICAL REVIEW B , v. 101, p. 125115, 2020.

• LOPES, VICTOR ; MARTINS, GEORGE ; MANYA, MARCO ; ANDA, ENRIQUE VICTORIANO . Kondo effect under the influence of spin-orbit coupling in a quantum wire. JOURNAL OF PHYSICS-CONDENSED MATTER , v. 32, p. 435604, 2020.

• MARTINS, G. B. ; VERNECK, E. ; ZITKO, R. . Anisotropic Kondo screening induced by spin-orbit coupling in quantum wires. Physical Review. B, Condensed Matter. (Cessou 1997. Cont. 1098-0121 Physical Review. B, Condensed Matter and Materials Physics) , v. 102, p. 5114, 2020.

• RIBEIRO, L. C. ; MARTINS, G. B. ; GÓMEZ-SILVA, G. ; ANDA, E. V. . Numerical study of the Kondo cloud using finite-U slave bosons. PHYSICAL REVIEW B , v. 99, p. 085139, 2019.

• CALLE, A M ; PACHECO, M ; MARTINS, G B ; APEL, V M ; LARA, G A ; ORELLANA, P A . Fano-Andreev effect in a T-shape double quantum dot in the Kondo regime. JOURNAL OF PHYSICS-CONDENSED MATTER , v. 29, p. 135301, 2017.

• MARTINS, GEORGE B ; MENDONCA, GRIFFITH ; CONTINENTINO, MUCIO ; OLIVEIRA, THARNIER . Multiband superconductivity in BiS2-based layered compounds. JOURNAL OF PHYSICS-CONDENSED MATTER , v. 29, p. 305601, 2017.

• LOPES, V. ; PADILLA, R. A. ; MARTINS, G. B. ; ANDA, E. V. . SU(4)-SU(2) crossover and spin-filter properties of a double quantum dot nanosystem. PHYSICAL REVIEW B , v. 95, p. 245133, 2017.

• ALLERDT, ANDREW ; FEIGUIN, A. E. ; MARTINS, G. B. . Spatial structure of correlations around a quantum impurity at the edge of a two-dimensional topological insulator. PHYSICAL REVIEW B , v. 96, p. 035109, 2017.

• ALLERDT, ANDREW ; FEIGUIN, A.E. ; MARTINS, G.B. . Kondo effect in a two-dimensional topological insulator: Exact results for adatom impurities. JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS , v. 11, p. 6, 2017.

• GRIFFITH, M.A ; FOYEVTSOVA, K ; CONTINENTINO, M.A ; MARTINS, G.B . Applying experimental constraints to a one-dimensional model for BiS2 superconductivity. SOLID STATE COMMUNICATIONS , v. 244, p. 57, 2016.

• GRIFFITH, M A ; FOYEVTSOVA, K ; CONTINENTINO, M A ; MARTINS, G B . One-dimensional model for BiS 2 superconductivity: analyzing the pressure effect over T c. JOURNAL OF PHYSICS. CONFERENCE SERIES (PRINT) , v. 683, p. 012004, 2016.

• ALLERDT, ANDREW ; BÜSSER, C. A. ; MARTINS, G. B. ; FEIGUIN, A. E. . Kondo versus indirect exchange: Role of lattice and actual range of RKKY interactions in real materials. Physical Review. B, Condensed Matter and Materials Physics , v. 91, p. 085101, 2015.

• VERNEK, E. ; BÜSSER, C. A. ; ANDA, E. V. ; FEIGUIN, A. E. ; MARTINS, G. B. . Spin filtering in a double quantum dot device: Numerical renormalization group study of the internal structure of the Kondo state. Applied Physics Letters , v. 104, p. 132401, 2014.

• ROMERO, JAVIER I. ; VERNEK, E. ; MARTINS, G. B. ; MUCCIOLO, E. R. . Magnetic-field-modulated Kondo effect in a single-magnetic-ion molecule. Physical Review. B, Condensed Matter and Materials Physics , v. 90, p. 195417, 2014.

• MARTINS, G. B. ; MOREO, A. ; DAGOTTO, E. . RPA analysis of a two-orbital model for the BiS_{2}-based superconductors. Physical Review B , v. 87, p. 081102, 2013.

• HAMAD, I. J. ; COSTA RIBEIRO, L. ; MARTINS, G. B. ; ANDA, E. V. . Transport properties of a two-impurity system: A theoretical approach. Physical Review B , v. 87, p. 115102, 2013.

• BÜSSER, C. ; MARTINS, G. ; FEIGUIN, A. . Lanczos transformation for quantum impurity problems in d -dimensional lattices: Application to graphene nanoribbons. Physical Review. B, Condensed Matter and Materials Physics , v. 88, p. 245113, 2013.

• RIBEIRO, L. C. ; VERNEK, E. ; MARTINS, G. B. ; ANDA, E. V. . Kondo temperature and screening extension in a double quantum dot system. Physical Review B , v. 85, p. 165401, 2012.

• BÜSSER, C. A. ; FEIGUIN, A. E. ; MARTINS, G. B. . Electrostatic control over polarized currents through the spin-orbital Kondo effect. Physical Review B , v. 85, p. 241310, 2012.

• BÃSSER, C. ; ORELLANA, P. ; FEIGUIN, A. ; KIM, E. ; MARTINS, G. ; ANDA, E. ; LARA, G. ; VERNEK, E. . Transport in carbon nanotubes: Two-level SU(2) regime reveals subtle competition between Kondo and intermediate valence states. Physical Review B , v. 83, p. 125404, 2011.

• NICHOLSON, ANDREW ; GE, WEIHAO ; ZHANG, XIAOTIAN ; RIERA, JOSÉ ; DAGHOFER, MARIA ; OLE', ANDRZEJ M. ; MARTINS, GEORGE B. ; MOREO, ADRIANA ; DAGOTTO, ELBIO . Competing Pairing Symmetries in a Generalized Two-Orbital Model for the Pnictide Superconductors. Physical Review Letters , v. 106, p. 217002, 2011.

• NICHOLSON, ANDREW ; LUO, QINLONG ; GE, WEIHAO ; RIERA, JOSÉ ; DAGHOFER, MARIA ; MARTINS, GEORGE B. ; MOREO, ADRIANA ; DAGOTTO, ELBIO . Role of degeneracy, hybridization, and nesting in the properties of multiorbital systems. Physical Review B , v. 84, p. 094519, 2011.

• FERREIRA, IRISNEI ; ORELLANA, P. ; MARTINS, G. ; SOUZA, F. ; VERNEK, E. . Capacitively coupled double quantum dot system in the Kondo regime. Physical Review. B, Condensed Matter and Materials Physics , v. 84, p. 205320, 2011.

• BÃSSER, C. A. ; VERNEK, E. ; DAGOTTO, E. ; MARTINS, G. B. ; ANDA, E. V. ; COSTA RIBEIRO, L. . Numerical analysis of the spatial range of the Kondo effect. Physical Review B , v. 81, p. 045111, 2010.

• LUO, QINLONG ; MARTINS, GEORGE ; YAO, DAO-XIN ; DAGHOFER, MARIA ; YU, RONG ; MOREO, ADRIANA ; DAGOTTO, ELBIO . Neutron and ARPES constraints on the couplings of the multiorbital Hubbard model for the iron pnictides. Physical Review B , v. 82, p. 104508, 2010.

• ANDA, E. V. ; CHIAPPE, G. ; BÜSSER, C. A. ; DAVIDOVICH, M. A. ; MARTINS, G. B. ; HEIDRICH-MEISNER, F. ; DAGOTTO, E. . A Perturbation Expansion Method to Study Highly Correlated Spins. Journal of Superconductivity and Novel Magnetism , v. 23, p. 145-148, 2010.

• VERNEK, E. ; MARTINS, G. ; BÃSSER, C. ; ULLOA, S. ; SANDLER, N. ; ANDA, E. . Kondo regime in triangular arrangements of quantum dots: Molecular orbitals, interference, and contact effects. Physical Review. B, Condensed Matter and Materials Physics , v. 80, p. 035119, 2009.

• HEIDRICH-MEISNER, F. ; MARTINS, G. B. ; BÜSSER, C. A. ; AL-HASSANIEH, K. A. ; FEIGUIN, A. E. ; CHIAPPE, G. ; ANDA, E. V. ; DAGOTTO, E. . Transport through quantum dots: a combined DMRG and embedded-cluster approximation study. European Physical Journal. B, Condensed Matter and CompleX Systems (Internet) , v. 67, p. 527-542, 2009.

• MIZUNO, M ; KIM, EUGENE H ; MARTINS, G B . Transport and strong-correlation phenomena in carbon nanotube quantum dots in a magnetic field. Journal of Physics. Condensed Matter (Online) , v. 21, p. 292203, 2009.

• ANDA, E.V. ; CHIAPPE, G. ; BÜSSER, C.A. ; DAVIDOVICH, M.A. ; MARTINS, G.B. ; HEIDRICH-MEISNER, F. ; DAGOTTO, E. . The logarithmic discretization embedded cluster approximation. Physica. B, Condensed Matter (Print) , v. 404, p. 2689-2693, 2009.

• AL-HASSANIEH, K. A. ; BÜSSER, C. A. ; MARTINS, G. B. . ELECTRON TRANSPORT IN STRONGLY CORRELATED NANOSTRUCTURES. Modern Physics Letters B , v. 23, p. 2193-2213, 2009.

• ANDA, E. ; HEIDRICH-MEISNER, F. ; MARTINS, G. ; BÃSSER, C. ; DAVIDOVICH, M. ; DAGOTTO, E. ; CHIAPPE, G. . Method to study highly correlated nanostructures: The logarithmic-discretization embedded-cluster approximation. Physical Review B , v. 78, p. 085308, 2008.

• MARTINS, GEORGE B ; BRENIG, WOLFRAM . Static holes in the geometrically frustrated bow-tie ladder. Journal of Physics. Condensed Matter (Online) , v. 20, p. 415204, 2008.

• DIAS DA SILVA, LUIS ; DAGOTTO, E. ; MARTINS, G. ; HEIDRICH-MEISNER, F. ; ANDA, E. ; BÃSSER, C. ; FEIGUIN, A. . Transport properties and Kondo correlations in nanostructures: Time-dependent DMRG method applied to quantum dots coupled to Wilson chains. Physical Review B , v. 78, p. 195317, 2008.

• MARTINS, G.B. ; BÜSSER, C.A. . Half-filling SU(4) Kondo state in carbon nanotubes: Numerical results. Physica. B, Condensed Matter (Print) , v. 403, p. 1514-1516, 2008.

• HEIDRICH-MEISNER, F. ; MARTINS, G.B. ; AL-HASSANIEH, K.A. ; FEIGUIN, A.E. ; DAGOTTO, E. . Finite-size scaling analysis of spin correlations and fluctuations of two quantum dots in a T-shape geometry. Physica. B, Condensed Matter (Print) , v. 403, p. 1544-1546, 2008.

• BÜSSER, C. ; MARTINS, G. . Numerical results indicate a half-filling SU(4) Kondo state in carbon nanotubes. Physical Review B , v. 75, p. 045406, 2007.

• MARTINS, G. ; BÜSSER, C. ; AL-HASSANIEH, K. ; ANDA, E. ; MOREO, A. ; DAGOTTO, E. . Transport Properties of Strongly Correlated Electrons in Quantum Dots Studied with a Simple Circuit Model. Physical Review Letters (Print) , v. 96, p. 066802-1-066802-4, 2006.

• MARTINS, G. ; DAGOTTO, E. ; MOREO, A. ; BÃSSER, C. ; AL-HASSANIEH, K. . Prediction of Ferromagnetic Correlations in Coupled Double-Level Quantum Dots. Physical Review Letters , v. 94, p. 026804, 2005.

• AL-HASSANIEH, K. ; BÜSSER, C. ; MARTINS, G. ; DAGOTTO, E. . Electron Transport through a Molecular Conductor with Center-of-Mass Motion. Physical Review Letters (Print) , v. 95, p. 256807, 2005.

• ALBUQUERQUE, A F ; MARTINS, G B . New results for the t - J model in ladders: changes in the spin liquid state with applied magnetic field; implications for the cuprates. Journal of Physics. Condensed Matter (Print) , v. 17, p. 2419-2434, 2005.

• BÜSSER, C. ; MARTINS, G. ; AL-HASSANIEH, K. ; MOREO, ADRIANA ; DAGOTTO, ELBIO . Interference effects in the conductance of multilevel quantum dots. Physical Review. B, Condensed Matter and Materials Physics , v. 70, p. 245303, 2004.

• FYE, R. ; MARTINS, G. ; DAGOTTO, E. . Hole-pair symmetry and excitations in the strong-coupling extended t-Jz model: competition between d-wave and p-wave symmetry. Physical Review. B, Condensed Matter and Materials Physics , v. 69, p. 224507, 2004.

• SORELLA, S. ; MARTINS, G. B. ; BECCA, F. ; GAZZA, C. ; CAPRIOTI, L. ; PAROLLA, A. ; DAGOTTO, E. . Superconductivity in the Two-Dimensional t-J Model. Physical Review Letters , Estados Unidos, v. 88, n.11, p. 117002, 2002.

• PAGLIUSO, P. G. ; THOMPSON, J. D. ; SARRAO, J. L. ; SERCHELI, M. S. ; RETTORI, C. ; MARTINS, G. B. ; FISK, Z. ; OSEROFF, S. B. . Crystal field study in rare-earth-doped LuInNi4. Physical Review. B, Condensed Matter. (Cessou 1997. Cont. 1098-0121 Physical Review. B, Condensed Matter and Materials Physics) , v. 63, n.14, p. 144430, 2001.

• MARTINHO, H. ; MORENO, N. O. ; SANJURJO, J. A. ; RETTORI, C. ; GARCIAADEVA, A. J. ; HUBER, D. L. ; OSEROFF, S. ; RATCLIFF, W. ; CHEONG, S. W. ; PAGLIUSO, P. G. ; SARRAO, J. L. ; MARTINS, G. B. . Studies of the three-dimensional frustrated antiferromagnetic ZnCr[sub 2]O[sub 4]. Journal of Applied Physics , v. 89, n.11, p. 7050, 2001.

• MARTINHO, H. ; MORENO, N. O. ; SANJURJO, J. A. ; RETTORI, C. ; GARCÍA-ADEVA, A. J. ; HUBER, D. L. ; OSEROFF, S. B. ; II, W. R. ; CHEONG, S. -. ; PAGLIUSO, P. G. ; SARRAO, J. L. ; MARTINS, G. B. . Magnetic properties of the frustrated antiferromagnetic spinel ZnCr2O4 and the spin-glass Zn1-xCdxCr2O4 (x=0.05,0.10). Physical Review B , v. 64, n.02, p. 024408, 2001.

• MARTINS, G. B. ; XAVIER, J. C. ; ARRACHEA, L. ; DAGOTTO, E. . Qualitative understanding of the sign of t- asymmetry in the extended t-J model and relevance for pairing properties. Physical Review. B, Condensed Matter. (Cessou 1997. Cont. 1098-0121 Physical Review. B, Condensed Matter and Materials Physics) , Estados Unidos, v. 64, n.18, p. R1805-R1805-4, 2001.

• CURRO, N. J. ; SIMOVIC, B. ; HAMMEL, P. C. ; PAGLIUSO, P. G. ; SARRAO, J. L. ; THOMPSON, J. D. ; MARTINS, G. B. . Anomalous NMR magnetic shifts in CeCoIn5. Physical Review B , Estados Unidos, v. 64, n.18, p. 180514, 2001.

• MARTINS, G. B. ; GAZZA, C. ; XAVIER, J. C. ; FEIGUIN, A. ; DAGOTTO, E. . Doped Stripes in Models for the Cuprates Emerging from the One-Hole Properties of the Insulator. Physical Review Letters (Print) , v. 84, n.25, p. 5844-5847, 2000.

• URBANO, R. R. ; GARCIA, A. ; GRANADO, E. ; SANJURJO, J. A. ; TORRIANI, I. ; RETTORI, C. ; OSEROFF, S. B. ; HASSAN, A. ; MARTINS, G. B. ; FISK, Z. ; PAGLIUSO, P. G. ; SARRAO, J. L. ; CACIUFFO, R. . Structural effects in the EPR spectra of in. Physical Review. B, Condensed Matter. (Cessou 1997. Cont. 1098-0121 Physical Review. B, Condensed Matter and Materials Physics) , v. 62, n.14, p. 9593-9598, 2000.

• MARTINS, G. B. ; GAZZA, C. ; DAGOTTO, E. . Stripes in the Ising limit of models for the cuprates. Physical Review. B, Condensed Matter. (Cessou 1997. Cont. 1098-0121 Physical Review. B, Condensed Matter and Materials Physics) , v. 62, n.21, p. 13926-13929, 2000.

• DAGOTTO, E. ; MARTINS, G. B. . Doped stripes evolving from the one-hole properties of the antiferromagnetic insulator. International Journal of Modern Physics B , v. 14, n.29-31, p. 3424-3431, 2000.

• MARTINS, G. B. ; XAVIER, J. C. ; GAZZA, C. ; VOJTA, M. ; DAGOTTO, E. . Indications of spin-charge separation at short distance and stripe formation in the extended t-J model on ladders and planes. Physical Review. B, Condensed Matter. (Cessou 1997. Cont. 1098-0121 Physical Review. B, Condensed Matter and Materials Physics) , v. 63, n.1, p. 014414-014414-13, 2000.

• GAZZA, C. ; MARTINS, G. B. ; RIERA, J. ; DAGOTTO, E. . Hole pairs in a spin liquid: Influence of electrostatic hole-hole repulsion. Physical Review. B, Condensed Matter. (Cessou 1997. Cont. 1098-0121 Physical Review. B, Condensed Matter and Materials Physics) , v. 59, n.2, p. R709-R712, 1999.

• MARTINS, G. B. ; GAZZA, C. ; DAGOTTO, E. . Hole-density evolution of the one-particle spectral function in doped ladders. Physical Review. B, Condensed Matter. (Cessou 1997. Cont. 1098-0121 Physical Review. B, Condensed Matter and Materials Physics) , v. 59, n.21, p. 13596-13599, 1999.

• PAGLIUSO, P. G. ; RETTORI, C. ; TORELLI, M. E. ; MARTINS, G. B. ; FISK, Z. ; SARRAO, J. L. ; HUNDLEY, M. F. ; OSEROFF, S. B. . Crystal-field study in rare-earth-doped semiconducting YBiPt. Physical Review. B, Condensed Matter. (Cessou 1997. Cont. 1098-0121 Physical Review. B, Condensed Matter and Materials Physics) , v. 60, n.6, p. 4176-4180, 1999.

• MARTINS, G. B. ; EDER, R. ; DAGOTTO, E. . Indications of spin-charge separation in the two-dimensional extended t-J model. Physical Review. B, Condensed Matter. (Cessou 1997. Cont. 1098-0121 Physical Review. B, Condensed Matter and Materials Physics) , v. 60, n.6, p. R3716-R3719, 1999.

• HASSAN, A. K. ; PARDI, L. A. ; MARTINS, G. B. ; CAO, G. ; BRUNEL, L. . High-Field Electron Spin Resonance of Cu1-xZnxGeO3. Physical Review Letters (Print) , v. 80, n.9, p. 1984-1987, 1998.

• SARRAO, J. ; MODLER, R. ; MOVSHOVICH, R. ; LACERDA, A. H. ; HRISTOVA, D. ; CORNELIUS, A. L. ; HUNDLEY, M. F. ; THOMPSON, J. D. ; BENTON, C. L. ; IMMER, C. D. ; TORRELI, M. E. ; MARTINS, G. B. ; FISK, Z. ; OSEROFF, S. B. . Ferromagnetism and crystal fields in YbInNi4. Physical Review. B, Condensed Matter. (Cessou 1997. Cont. 1098-0121 Physical Review. B, Condensed Matter and Materials Physics) , v. 57, n.13, p. 7785-7790, 1998.

• LAUKAMP, M. ; MARTINS, G. B. ; GAZZA, C. ; MALVEZZI, A. L. ; DAGOTTO, E. ; HANSEN, P. M. ; LOPEZ, A. C. ; RIERA, J. . Enhancement of antiferromagnetic correlations induced by nonmagnetic impurities: Origin and predictions for NMR experiments. Physical Review. B, Condensed Matter. (Cessou 1997. Cont. 1098-0121 Physical Review. B, Condensed Matter and Materials Physics) , v. 57, n.17, p. 10755-10769, 1998.

• DAGOTTO, E. ; MARTINS, G. B. ; RIERA, J. ; MALVEZZI, A. L. ; GAZZA, C. . Diagonalization in reduced Hilbert spaces using a systematically improved basis: Application to spin dynamics in lightly doped ladders. Physical Review. B, Condensed Matter. (Cessou 1997. Cont. 1098-0121 Physical Review. B, Condensed Matter and Materials Physics) , v. 58, n.18, p. 12063-12070, 1998.

• MARTINS, G. B. ; LAUKAMP, M. ; RIERA, J. ; DAGOTTO, E. . Local Enhancement of Antiferromagnetic Correlations by Nonmagnetic Impurities. PHYSICAL REVIEW LETTERS , v. 78, n.18, p. 3563-3566, 1997.

• RETTORI, C. ; RAO, D. ; VALDIVIA, J. A. ; BARBERIS, G. E. ; MARTINS, G. B. ; SARRAO, J. ; FISK, Z. ; TOVAR, M. . ESR of Gd3+ in magnetically ordered Eu2CuO4. Physical Review. B, Condensed Matter. (Cessou 1997. Cont. 1098-0121 Physical Review. B, Condensed Matter and Materials Physics) , v. 54, n.2, p. 1123-1127, 1996.

• MARTINS, G. B. ; DAGOTTO, E. ; RIERA, J. . Rapid suppression of the spin gap in Zn-doped CuGeO3 and SrCu2O3. Physical Review. B, Condensed Matter. (Cessou 1997. Cont. 1098-0121 Physical Review. B, Condensed Matter and Materials Physics) , v. 54, n.22, p. 16032-16038, 1996.

• SANJURJO, J. A. ; MARTINS, G. B. ; PAGLIUSO, P. G. ; GRANADO, E. ; TORRIANI, I. ; RETTORI, C. ; OSEROFF, S. ; FISK, Z. . Different environments in : A Raman crystal-field excitation study. Physical Review. B, Condensed Matter. (Cessou 1997. Cont. 1098-0121 Physical Review. B, Condensed Matter and Materials Physics) , v. 51, n.2, p. 1185-1189, 1995.

• MARTINS, G. B. ; RAO, D. ; VALDIVIA, J. A. ; PIRES, M. A. ; BARBERIS, G. E. ; RETTORI, C. ; VENEGAS, P. A. ; OSEROFF, S. ; FISK, Z. . ESR of Gd3+ and Er3+ in Pr2-xCexCuO4. Physical Review. B, Condensed Matter. (Cessou 1997. Cont. 1098-0121 Physical Review. B, Condensed Matter and Materials Physics) , v. 51, n.17, p. 11909-11914, 1995.

• MARTINS, G. B. ; RAO, D. ; BARBERIS, G. E. ; RETTORI, C. ; DURO, R. J. ; SARRAO, J. ; FISK, Z. ; OSEROFF, S. ; THOMPSON, J. D. . Electron spin resonance of Er3+ in YBiPt. Physical Review. B, Condensed Matter. (Cessou 1997. Cont. 1098-0121 Physical Review. B, Condensed Matter and Materials Physics) , v. 52, n.21, p. 15062-15065, 1995.

• BARBERIS, G. E. ; MARTINS, G. B. ; CALVO, R. . Spin-lattice interaction for ions in low-symmetry sites: The case of Mn2+:CaCO3. Physical Review. B, Condensed Matter. (Cessou 1997. Cont. 1098-0121 Physical Review. B, Condensed Matter and Materials Physics) , v. 49, n.13, p. 8583-8590, 1994.

• MARTINS, G. B. ; PIRES, M. A. ; BARBERIS, G. E. ; RETTORI, C. ; TORIKACHIVILI, M. S. . Electron spin resonance of Nd3+ and Yb3+ in CdFe4P12. Physical Review. B, Condensed Matter. (Cessou 1997. Cont. 1098-0121 Physical Review. B, Condensed Matter and Materials Physics) , v. 50, n.20, p. 14822-14826, 1994.

• GENNARO, A.M. ; MARTINS, G.B. ; RETTORI, C. ; BARBERIS, G.E. ; AN, C.Y. . Esr of Rare Earth Impurities (Dy3+, Er3+, Yb3+) in The Narrow Gap Semiconductor PbTE.. MRS PROCEEDINGS , v. 301, p. 213-218, 1993.

• MARTINS, G. ; Almeida, P. A. ; Sergio Ulloa ; Marcos Sergio ; MANYA, MARCO ; ANDA, ENRIQUE VICTORIANO . Fractional Kondo state near a band singularity in one-dimensional systems. 2023. (Apresentação de Trabalho/Congresso).

• MARTINS, G. ; VERNEK, E. ; DINIZ, G. S. . The Kondo effect as a probe of the topological properties of the Kane-Mele model. 2022. (Apresentação de Trabalho/Congresso).

• MARTINS, G. . Ferromagnetism in armchair graphene nanoribbon heterostructures. 2021. (Apresentação de Trabalho/Seminário).

• MARTINS, G. ; CASSIANO, JOÃO VICTOR VILELA . Electric-Field-Generated Topological States in a Silicene Nanotube. 2021. (Apresentação de Trabalho/Congresso).

• MARTINS, G. ; CASSIANO, JOÃO VICTOR VILELA . Electric-Field-Generated Topological States in a Silicene Nanotube. 2020. (Apresentação de Trabalho/Seminário).

• GEORGE MARTINS . Kondo in 1d and quasi-1d spin-orbit-coupled environments: Rashba quantumwire and Silicene zigzag nanoribbons. 2019. (Apresentação de Trabalho/Congresso).

• MARTINS, G.B . Topology and New materials. 2017. (Apresentação de Trabalho/Seminário).

• ALLERDT, ANDREW ; Adrian Feiguin ; MARTINS, G.B . Competition between Kondo and indirect exchange at the edges and bulk of graphene, and 2D materials.. 2016. (Apresentação de Trabalho/Congresso).

• MARTINS, G.B . New 2d topological materials: Silicene, a case study. 2016. (Apresentação de Trabalho/Seminário).

• ALLERDT, ANDREW ; BÜSSER, C. A. ; FEIGUIN, A. E. ; G. B. MARTINS . Kondo versus indirect exchange: the role of the lattice and the actual range of RKKY interactions in real materials. 2015. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS . Is BiS2 a one-dimensional superconductor?. 2015. (Apresentação de Trabalho/Conferência ou palestra).

• G. B. MARTINS . BiS2 compounds: Properties, effective low-energy models and RPA results. 2014. (Apresentação de Trabalho/Conferência ou palestra).

• G. B. MARTINS . BiS2 compounds: Properties, effective low-energy models and RPA results. 2014. (Apresentação de Trabalho/Conferência ou palestra).

• G. B. MARTINS . RPA Analysis of a Two-orbital Model for the BiS2-based Superconductors. 2014. (Apresentação de Trabalho/Congresso).

• MUCCIOLO, E. R. ; VERNEK, E. ; ROMERO, JAVIER I. ; G. B. MARTINS . Kondo effect signatures in the electronic transport through a single-ion magnet under an applied transverse magnetic field. 2014. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS . BiS2 compounds: Properties, effective low-energy models and RPA results. 2013. (Apresentação de Trabalho/Conferência ou palestra).

• G. B. MARTINS . BiS2 compounds: Properties, effective low-energy models and RPA results. 2013. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS ; DAGOTTO, E. ; MOREO, ADRIANA . BiS2 compounds: Properties, effective low-energy models and RPA results. 2013. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS ; HAMAD, I. J. ; ANDA, E. V. ; RIBEIRO, L. C. . Transport properties of a two impurity system: a theoretical approach. 2013. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS ; DAGOTTO, ELBIO . Superconductivity in two-leg ladder iron selenides. 2013. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS ; ULLOA, S. ; VERNEK, E. . Decoherence effects of a charge detector on a nearby quantum dot. 2013. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS ; DAGOTTO, ELBIO ; MOREO, ADRIANA . Role of Degeneracy, Hybridization, and Nesting in the Properties of Multi-Orbital Systems. 2012. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS ; FEIGUIN, A. E. ; BÜSSER, C. A. . Capacitively coupled double quantum dot system in the Kondo regime. 2012. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS . Electrostatic control over polarized currents through spin-orbital Kondo effect. 2012. (Apresentação de Trabalho/Conferência ou palestra).

• G. B. MARTINS . Electrostatic control over polarized currents through spin-orbital Kondo effect. 2012. (Apresentação de Trabalho/Conferência ou palestra).

• G. B. MARTINS . The Logarithmic Discretization Embedded Cluster Approximation (LDECA). 2012. (Apresentação de Trabalho/Conferência ou palestra).

• G. B. MARTINS ; FEIGUIN, A.E. ; BÜSSER, C. A. . Magnetic impurities in real lattices: A DMRG and ECA study. 2011. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS ; DAGOTTO, ELBIO ; MOREO, ADRIANA . Competing Pairing Symmetries in a Generalized Two-Orbital Model for the Pnictides. 2011. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS ; BÜSSER, C. A. ; FEIGUIN, A.E. . Transport in Carbon Nanotubes: 2LSU(2) regime reveals subtle competition between Kondo and Intermediate Valence states. 2011. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS ; DAGOTTO, ELBIO ; MOREO, ADRIANA . Neutron and ARPES constraints on the couplings of the multiorbital Hubbard model for the iron pnictides. 2011. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS . Iron-pnictides: A brief introduction, effective low-energy models and RPA results. 2011. (Apresentação de Trabalho/Conferência ou palestra).

• G. B. MARTINS . Introduction to Mesoscopic Charge Transport. 2011. (Apresentação de Trabalho/Conferência ou palestra).

• G. B. MARTINS . 2LSU(2) regime: a switch between Kondo and Intermediate Valence. 2011. (Apresentação de Trabalho/Conferência ou palestra).

• G. B. MARTINS . 2LSU(2) regime: competition between Kondo and Intermediate Valence (a numerical collaboration). 2011. (Apresentação de Trabalho/Conferência ou palestra).

• G. B. MARTINS ; BÜSSER, C. A. . Carbon Nanotubes: from SU4 to Dicke effect. 2010. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS ; DAGOTTO, ELBIO ; MOREO, ADRIANA . Electronic Structures of Parent Compounds of Iron Pnictides: Study Using a Five-Orbital Model. 2010. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS ; KIM, EUGENE H ; MIZUNO, M . Transport and Strong-Correlation Phenomena in Carbon Nanotube Quantum Dots in a Magnetic Field. 2010. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS . Iron-pnictides: A brief introduction, effective low-energy models and RPA results. 2010. (Apresentação de Trabalho/Conferência ou palestra).

• G. B. MARTINS . 2LSU(2) regime: competition between Kondo and Intermediate Valence (a numerical collaboration). 2010. (Apresentação de Trabalho/Conferência ou palestra).

• MARTINS, G B . Numerical analysis of the 2LSU(2) regime in carbon nanotubes. 2010. (Apresentação de Trabalho/Conferência ou palestra).

• G. B. MARTINS . The Logarithmic Discretization Embedded Cluster Approximation (LDECA). 2010. (Apresentação de Trabalho/Conferência ou palestra).

• G. B. MARTINS ; BÜSSER, C. A. ; ANDA, E. V. ; VERNEK, E. . Spatial range of the Kondo effect. 2009. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS ; BÜSSER, C. A. ; VERNEK, E. ; ANDA, E. V. ; ULLOA, S. ; SANDLER, N. . Interference in triple quantum dot systems. 2009. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS . Iron-pnictides: A brief introduction, effective low-energy models and RPA results. 2009. (Apresentação de Trabalho/Conferência ou palestra).

• G. B. MARTINS . Iron-pnictides: A brief introduction, effective low-energy models and RPA results. 2009. (Apresentação de Trabalho/Conferência ou palestra).

• G. B. MARTINS . The Logarithmic Discretization Embedded Cluster Approximation (LDECA). 2009. (Apresentação de Trabalho/Conferência ou palestra).

• G. B. MARTINS . The Logarithmic Discretization Embedded Cluster Approximation (LDECA). 2009. (Apresentação de Trabalho/Conferência ou palestra).

• G. B. MARTINS . The Logarithmic Discretization Embedded Cluster Approximation (LDECA). 2009. (Apresentação de Trabalho/Conferência ou palestra).

• G. B. MARTINS . Application of the Cluster Embedding Method to Transport Through Anderson Impurities. 2009. (Apresentação de Trabalho/Conferência ou palestra).

• G. B. MARTINS . The Logarithmic Discretization Embedded Cluster Approximation (LDECA). 2008. (Apresentação de Trabalho/Conferência ou palestra).

• G. B. MARTINS ; BRENIG, WOLFRAM . Defects in the geometrically frustrated bow tie ladder. 2007. (Apresentação de Trabalho/Conferência ou palestra).

• G. B. MARTINS . Transport Properties of Strongly Correlated Electrons in Quantum Dots Using a Simple Circuit Model. 2006. (Apresentação de Trabalho/Conferência ou palestra).

• G. B. MARTINS ; BÜSSER, C. A. ; AL-HASSANIEH, K. A. ; DAGOTTO, ELBIO . Transport properties of strongly correlated electrons in quantum dots studied with a simple circuit model. 2005. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS ; BÜSSER, C. A. ; AL-HASSANIEH, K.A. ; DAGOTTO, ELBIO . Numerical evidence of tunable long-range spin interactions between quantum dots. 2005. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS ; BÜSSER, C.A. ; AL-HASSANIEH, K.A. ; DAGOTTO, ELBIO . Coupled Double-level Quantum Dots: Kondo Effect in Presence of Ferromagnetism. 2004. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS ; ALBUQUERQUE, A F . Magnetic-Field-Induced Antiferromagnetism in the t J Model. 2004. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS ; EDER, R. ; DAGOTTO, E. . Qualitative understanding of the sign of t0 asymmetry in the extended tJ Model and relevance for pairing properties. 2002. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS ; XAVIER, J. C. ; GAZZA, C. ; FEIGUIN, A. ; DAGOTTO, E. . Doped Stripes in Models for the Cuprates Emerging from the One-hole Properties of the Insulator. 2001. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS ; DAGOTTO, E. . Dynamic and Static Properties of Hole-Doped 4-leg Ladders Using the Optimized Reduced Basis Approximation (ORBA) Method. 1999. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS ; DAGOTTO, E. . Evolution of the quasiparticle dispersion of the tJ model at low hole concentration using an improved truncated Lanczos procedure. 1998. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS ; GAZZA, C. ; DAGOTTO, E. . Study of the two-hole bound state in the t J model including a short-range hole-hole Coulomb repulsion. 1998. (Apresentação de Trabalho/Congresso).

• G. B. MARTINS ; DAGOTTO, E. . Many-body basis-set reduction applied to the two-dimensional t J model with holes. 1997. (Apresentação de Trabalho/Congresso).

Outras produções

Projetos de pesquisa

• 2023 - Atual

  RKKY interaction in Silicene Nanoribbons, Descrição: Using the Lanczos Projection Method, coupled to the Density Matrix Renormalization Group, to study the RKKY interaction promoted by a metallic helical state present at the edge of a 2d Topological Insulator.. , Situação: Em andamento; Natureza: Pesquisa. , Alunos envolvidos: Mestrado acadêmico: (1) . , Integrantes: George Balster Martins - Coordenador / FEIGUIN, A. E. - Integrante.

• 2022 - Atual

  Study of the Kondo cloud in a two-stage Kondo system, Descrição: We study the Kondo cloud in a DQD T-shape geometry, viz., one embedded QD (denoted QD1) and one side-connected (lateral) QD (denoted QD0).. , Situação: Em andamento; Natureza: Pesquisa. , Alunos envolvidos: Doutorado: (1) . , Integrantes: George Balster Martins - Coordenador / VERNEK, E. - Integrante / ANDA, ENRIQUE VICTORIANO - Integrante / Patricia de Assis Almeida - Integrante / Gustavo Lara - Integrante.

• 2022 - Atual

  Two-stage-Kondo effect: NRG results and Friedel Sum Rule, Descrição: We study the Friedel Sum Rule in a Two-Stage-Kondo system. , Situação: Em andamento; Natureza: Pesquisa. , Alunos envolvidos: Doutorado: (1) . , Integrantes: George Balster Martins - Coordenador / Edson Verneck - Integrante / ANDA, ENRIQUE VICTORIANO - Integrante / Patricia de Assis Almeida - Integrante / Sergio Ulloa - Integrante.

• 2022 - Atual

  Kondo effect near a Van-Hove singularity, Descrição: We study a Kondo state that is strongly influenced by its proximity to an #969;^#8722;1/2 singularity in the metallic host density of states.. , Situação: Em andamento; Natureza: Pesquisa. , Alunos envolvidos: Doutorado: (1) . , Integrantes: George Balster Martins - Coordenador / MARCOS SERGIO FIGUEIRA DA SILVA - Integrante / MANYA, MARCO - Integrante / ANDA, ENRIQUE VICTORIANO - Integrante / Patricia de Assis Almeida - Integrante / Sergio Ulloa - Integrante.

• 2022 - Atual

  Unconventional supreconductivity in magic-angle twisted bilayer graphene, pnictides, and nickelates., Descrição: We study the spin and charge quantum fluctuations, at the Random Phase Approximation level, that may favor a strong-coupling superconducting instability in three different materials:i) Magic Angle Twisted Bilayer Grapheneii) Pnictidesiii) Nickelates. , Situação: Em andamento; Natureza: Pesquisa. , Alunos envolvidos: Mestrado acadêmico: (1) Doutorado: (1) . , Integrantes: George Balster Martins - Coordenador / DIAS DA SILVA, LUIS - Integrante / DAGOTTO, ELBIO - Integrante.

• 2020 - Atual

  Topological Properties of Graphene Heterostructures using the Su-Schrieffer-Heeger model., Descrição: We study the properties of flat-bands that appear in a heterostructure composed of strands of different widths of graphene armchair nanoribbons. One of the flat-bands is reminiscent of the one that appears in pristine armchair nanoribbons and has its origin in a quantum mechanical destructive interference effect. The others, some closer to the Fermi level, seem to be generated by a similar interference process. After doing a thorough tight-binding analysis of the band structures of the different kinds of heterostructures, focusing in the properties of the flat-bands, we use Density Functional Theory to study the possibility of magnetic ground states when placing, through doping, the Fermi energy close to the different flat-bands.. , Situação: Em andamento; Natureza: Pesquisa. , Alunos envolvidos: Graduação: (1) / Mestrado acadêmico: (1) . , Integrantes: George Balster Martins - Coordenador / Tomé Mauro Schimdt - Integrante / Patricia de Assis Almeida - Integrante / Lucas Soares Souza - Integrante., Número de produções C, T & A: 2

• 2020 - Atual

  Influence of spin-orbit interaction in the Kondo effect, Descrição: Study of the Kondo effect in different systems subjected to spin-orbit interaction:i) quantum wiresii) silicene zigzag nanoribbonsiii) Two dimensional electron gas in the Persistent Spin Helix regime. , Situação: Em andamento; Natureza: Pesquisa. , Integrantes: George Balster Martins - Coordenador / Edson Verneck - Integrante / DINIZ, G. - Integrante / Rok Zitko - Integrante / Thanier Puel de Oliveira - Integrante., Número de produções C, T & A: 2

• 2019 - 2021

  Topological phase transition in a Silicene nanotube, Descrição: Applying an external electric field to a Silicene nanotube (perpendicular to its axis), we numerically study the two induced topological phase transitions occurring in this system: (i) by creating a topologically trivial region in the laterals of the nanotube, localized states are induced at the edge between the trivial and non-trivial regions. Applying a further electric field, orthogonal to both the tube axis and the first field applied) the nontrivial region is erased and the localized state is suppressed.. , Situação: Concluído; Natureza: Pesquisa. , Alunos envolvidos: Graduação: (1) / Mestrado acadêmico: (1) . , Integrantes: George Balster Martins - Coordenador., Número de produções C, T & A: 2

• 2018 - 2021

  Study of Edge States in Graphene and Silicene Zigzag Nanoribbons, Descrição: In this project, we will study the edge states of a Graphene and Silicene Zigzag Nanoribbon (GZNR). Graphene, a monolayer of Carbon, the building-block of graphite, was isolated in 2002 by Andre Geim and Konstantin Novoselov [(Science 306, 666 (2004)]. Since then, it has become one of the most studied materials in Condensed Matter Physics. The interest has only increased with the discovery of Topological Insulators (TI), which host spin-locked helical states at their surface, holding the promise of producing devices that allow the electric-field-control of dissipationless spin currents (the Holy Grail of spintronics). Although Graphene is not a TI, thus the electron spin is not locked to its momentum, a GZNR contains well localized edge states, thus it serves as a good starting point to study the details and subtle effects that occur in real TI materials, like Silicene (hexagonal monolayer of Silicon), which is a close cousin of Graphene. Indeed, a Silicene ZNR displays all the fundamental non-trivial topological properties that were first described in a seminal paper by Charlie Kane and Eugene Mele [Phys. Rev. Lett. 95, 146802 (2005)].. , Situação: Concluído; Natureza: Pesquisa. , Alunos envolvidos: Graduação: (2) / Mestrado acadêmico: (1) . , Integrantes: George Balster Martins - Coordenador., Número de produções C, T & A: 1

• 2016 - Atual

  Study of the Kondo state in Topological Insulators and systems with strong spin orbit interaction, Descrição: Metallic systems with strong spin orbit interaction, be it in 1D, 2D, or 3D, impart relativistic properties to the conduction electrons, the most important being the locking of spin orientation of the electron to its direction of movement. This has the potential to substantially affect the properties of a magnetic impurity doped into such a metallic host. In particular, we are interested in verifying how this affects the Kondo state of the impurity. In addition, Topological Insulators contain metallic surface states that can also screen a magnetic impurity, given origin to even more subtle and interesting changes of the resulting Kondo state.. , Situação: Em andamento; Natureza: Pesquisa. , Alunos envolvidos: Mestrado acadêmico: (1) Doutorado: (1) . , Integrantes: George Balster Martins - Coordenador / MARCOS SERGIO FIGUEIRA DA SILVA - Integrante / Edson Verneck - Integrante / Ginetom Diniz - Integrante / Adrian Feiguin - Integrante., Número de produções C, T & A: 2

• 2014 - 2018

  Supercondutividade de Alta Temperatura Crítica em Novos Materiais, Descrição: O tema deste projeto é o estudo teórico de novos materias supercondutores de alta temperatura crítica (alta-Tc). Um dos objetivos centrais é a integração do uso de métodos numéricos (Martins) e métodos analíticos (Continentino). Prof. Martins tem ampla experiência em métodos numéricos aplicados a sistemas de elétrons fortemente correlacionados e Prof. Continentino tem ampla experiência em técnicas analíticas aplicadas ao mesmo tipo de sistemas. Os sistemas que serão o foco desta colaboração são os chamados ?supercondutores de Ferro? (SF), também referidos pelo termo ?pnicitidas?. Tais materiais, descobertos em 2008, cite{Kamihara2008}, cite{Xiao-Wen2008}, estão na fronteira do conhecimento em Matéria Condensda e representam uma revolução na área de sistemas de elétrons fortemente correlacionados. Desde a descoberta de supercondutividade no material LaOFeAs com Tc=26K (numa amostra obtida através da substituição de Oxigênio por Fluor) uma procura bibliográfica no tópico ?pnictides?, resulta em mais de 1.700 publicações (com um total de 26.000 citações), enquanto o artigo relatando a descoberta já recebeu mais de 3.500 citações, num espaço de apenas 5 anos. Estes materiais, a serem descritos abaixo em mais detalhe, têm recebido relativamente pouca atenção no Brasil, principalmente na área teórica. É imperativo que um vigoroso programa de pesquisa nesta área seja estabelecido. Esta é a principal motivação para trazer Prof. Martins ao Brasil.. , Situação: Concluído; Natureza: Pesquisa. , Alunos envolvidos: Doutorado: (2) . , Integrantes: George Balster Martins - Coordenador / Mucio Amado Continentino - Integrante., Financiador(es): Conselho Nacional de Desenvolvimento Científico e Tecnológico - Cooperação., Número de produções C, T & A: 3

• 2011 - 2014

  Materials World Network - Collaborative Research: Symmetry, Local-Environment and Time-Dependent Effects in Nanoscale Systems: A Synergistic Approach, Descrição: The striking ability of experiments to probe correlations down to individual atomic environments has given rise to a host of questions not considered in bulk materials. Correlations between spins, their coupling to orbital motion, competition between Kondo phases and ordering of magnetic impurities, quantum phase transitions probed locally, and effects of decoherence, are but a few of the issues now explored in experiments. Our efforts are directed to addressing these issues, which are intrinsically important to basic physics. Moreover, the materials and systems of interest have great potential for applications in different areas: from nanomagnetism and spintronics, to new carbon-based electronic devices, and even quantum information. We believe our results will contribute to accelerate the realization of some of these ideas.. , Situação: Concluído; Natureza: Pesquisa. , Alunos envolvidos: Doutorado: (2) . , Integrantes: George Balster Martins - Coordenador., Financiador(es): National Science Foundation - Cooperação.

• 2009 - 2013

  Developing RPA and FLEX packages in Fortran 95, Descrição: The recent discovery that Iron-pnictide materials (either through doping or under pressure) are part of a new class of High-Tc superconductors (currently with a maximum Tc = 55K) has brought renewed interest into strongly correlated superconductors. Although there are clear similarities between the cuprates and the Ironpnictides, there are also important differences which call for a change of approach in developing numerical tools aimed at understanding their superconducting properties. The two most important differences are: First, it seems clear that the minimal effective model that can correctly capture the essential features of the Iron-pnictides around the Fermi surface is a multi-band model. Some research groups claim that all five Iron 3d orbitals, due to the strong hybridization of adjacent 3d orbitals through ?bridging? p orbitals, should be present in the effective model, while other groups advocate the use of a simpler model with three 3d orbitals (or possibly four 3d orbitals). Second, as a consequence, the most popular effective model to describe the electron correlations in the Iron-pnictides is the (multi-band) Hubbard model (also including a Hund?s coupling term). However, differently from the cuprates, which have an on-site Coulomb repulsion value that locates them in the strong coupling regime, the Iron-pnictides (which are semi-metals when undoped) have an on-site Coulomb repulsion that places them in the intermediate coupling regime, which is well known to be a very difficult regime to treat. On the one hand, the combination of these two factors rules out a series of numerical techniques that have been used extensively to study models for the cuprates, but, on the other hand, it opens up the possibility of using well established techniques like the Random-phase Approximation (RPA) and the Fluctuation Exchange Approximation (FLEX). While the RPA is a summation of all bubble (also called ring) diagrams, FLEX is a self-consistent summation of all bubble and ladder diagrams.. , Situação: Concluído; Natureza: Pesquisa. , Alunos envolvidos: Doutorado: (3) . , Integrantes: George Balster Martins - Coordenador., Financiador(es): Department of Energy - Remuneração., Número de produções C, T & A: 1

• 2007 - 2010

  Materials World Network: Collaborative Research: Decoherence, Correlations and Spin Effects in Nanostructured Materials, Descrição: This project aims to expand and deepen the understanding of correlated electron behavior in different material systems: magnetic adatoms and molecules on surfaces, carbon nanotubes and graphene, and quantum dots in semiconductors and other materials. Proposed work focuses on understanding and guiding experimental developments in these materials. Our goal is to provide physical insights into correlations and predictions concerning their measurement using newly developed probes (including scanning probes such as STM and spin-polarized STM) that explore local interactions with unprecedented spatial resolution. Our approach employs different theoretical techniques, including the numerical renormalization group and the embedded cluster approximation. These approaches are proven and reliable in treating nontrivial correlated problems, and their complementarity gives the collaboration a unique advantage. In addition to tackling specific problems, we propose to further advance the techniques to enhance their range of applicability.. , Situação: Concluído; Natureza: Pesquisa. , Alunos envolvidos: Doutorado: (1) . , Integrantes: George Balster Martins - Coordenador., Financiador(es): National Science Foundation - Cooperação.

• 2006 - 2008

  REU Site: Materials Measurements and Modeling, Descrição: The faculty in the Physics Department at Oakland University excels in providing research opportunities for undergraduates. Our first 3-year program (2006-2008), resulted in 10 published and/or submitted peer reviewed publications, and 9 conference posters and/or talks, in fields varying from Nanotechnology to Medical Physics. Students participated in conferences as far away as Washington DC and Los Angeles. The new version of SMaRT will double the number of mentors, and increase by more than 50% the number of students, providing a better ratio (almost 1 to 1) of students to mentors. Our Department, and the College of Arts and Sciences, are committed to transforming SMaRT into one of the role models of our mission of providing the highest quality undergraduate research. The multidisciplinary team assembled, combined with a variety of research-centered activities, like tutorials, ethics course, research intensive field trips, in a relaxed atmosphere provided by a small University campus, will serve as a template for gradual expansion through incorporation of more disciplines (biology and mathematics), that we hope to accomplish in the near future.. , Situação: Concluído; Natureza: Pesquisa. , Alunos envolvidos: Graduação: (24) . , Integrantes: George Balster Martins - Coordenador., Financiador(es): National Science Foundation - Cooperação.