Vítor J. Rocha Vieira (vrv@cfif.ist.utl.pt)

Vítor João Rocha Vieira

351-218419088

Main research interests

• Strongly correlated electron and spin systems.
• Low-dimensional systems.
• Electronic systems with magnetic impurities (Heisenberg and Kondo models).
• Haldane gap and influence of long-range interactions.
• Phase space representations of quantum mechanics. WKB.
• Feynman path integral.
• Non-perturbative methods: saddle point, loop and 1/n expansions, renormalization group.
• Systems far from equilibrium, real time formalisms.
• Quantum stochastic processes.
• Quantum information and computation.
• Quantum Monte Carlo and transfer matrix.

Selected papers

• "Kondo lattice: renormalization study using a new pseudofermion representation", V. R. Vieira, Phys. Rev. B 23, 6043-6054 (1981).
• "New field theoretical method for spin 1/2", V. R. Vieira, Physica 115A, 58-84 (1982).
• "Magnetic properties of ferromagnetic transition metals above TC: qualitative aspects", H. Capellmann and V. R. Vieira, Phys. Rev. B 25, 3333-3349 (1982).
• "New method for studying disordered quantum systems", H. G. Schuster and V. R. Vieira, Phys. Rev. B 34, 189-198 (1986).
• "The Helmholtz Free-Energy Functional for Quantum Spin 1/2 Systems'', P. D. Sacramento e V. R. Vieira, J. Phys. C 21, 3099-3131 (1988).
• "Finite temperature real time field theories for spin 1/2", V. R. Vieira, Phys. Rev. B 39, 7174-7195 (1989).
• "Relevance of the imaginary time branch in real time formalisms for thermodynamic equilibrium: study of the Heisenberg model", V. R. Vieira and I. R. Pimentel, Phys. Rev. B 39, 7196-7204 (1989).
• "Quantum Monte Carlo algorithms using coherent states" V. R. Vieira and P. D. Sacramento, Physica A 207, 584-607 (1994).
• "Closed-form relations for phase-space representatives of spin-J operators"V. R. Vieira and P. D. Sacramento, J. Phys. A 27, L783-L788 (1994).
• "Generalized phase-space representatives of spin-J operators in terms of Bloch coherent states", V. R. Vieira and P. D. Sacramento, Annals of Physics 242, 188-231 (1995).
• "Path integrals of spin-J systems in the holomorphic representation", V. R. Vieira and P. D. Sacramento, Nuclear Physics B 448, 331-354 (1995).
• "Finite-temperature correlation functions of the Haldane-Shastry model", P. D. Sacramento and V. R. Vieira, J. Phys.: Condens. Matter 7, 8619-8628 (1995).
• "Haldane Gap in a $S=1$ Exchange Model with Long-Range Interactions", P. D. Sacramento and V. R. Vieira, Z. Phys. B 101, 441-445 (1996).

Recent papers

• "Haldane Gap in the $S=1$ Haldane-Shastry Model", P. D. Sacramento and V. R. Vieira, Z. Phys. B 103, 231-233 (1997).
• "Gapless Spectrum in a Class of $S=1$ Exchange Models with Long-Range Interactions, P. D. Sacramento and V. R. Vieira, J. Phys. Cond. Matter 9, 10687-10700 (1997).
• "Spin-Density Wave in Ising-Coupled Antiferromagnetic Chains", J. P. Rodriguez, P. D. Sacramento and V. R. Vieira, Phys. Rev. B 56, 13685-13688 (1997).
• "Lattice coherence versus incoherent metal in the lattice n-channel Kondo model", P. D. Sacramento and V. R. Vieira. Phys. Rev. B 58, 11119-11122 (1998).
• "Spinor description of a general spin-J system", V. R. Vieira and P. D. Sacramento, in Albeverio S. Ph. Blanchard, L. Ferreira, T. Hida, Y. Kondratiev and R. V. Mendes, edts. Mathematical Physics and Stochastic Analysis--Essays in Honour of Ludwig Streit, (World Scientific, 2000).
• "Superconductivity in the SU(N) Anderson Lattice at U infinity", M. A. N. Araújo, N. M. R. Peres, P. D. Sacramento and V. R. Vieira, Physical Review B 62, 9800 (2000).
• "Decoupling of the S=1/2 antiferromagnetic zig-zag ladder with anisotropy", V. R. Vieira, N. Guihery, J. P. Rodriguez and P. D. Sacramento, Physical Review B 63, 224417 (2001).
• "Spin dynamics of the S=1/2 antiferromagnetic zig-zag ladder with anisotropy", P. D. Sacramento and V. R. Vieira, J. Phys. Cond. Matter 14, 591 (2002).
• "Non-equilibrium properties of the S=1/2 Heisenberg model in a time-dependent magnetic field", V. Turkowski, V. R. Vieira and P. D. Sacramento, Physica A 327, 461-476 (2003).
• "Spin accumulation, spin currents, and torque, in the problem of motion of a sharp domain wall in magnetic nanowires", V. R. Vieira, V. K. Dugaev, P. D. Sacramento, J. Barnaś, M. A. N. Araújo and J. Berakdar, Physica Status Solidi B 243, 193-196 (2006).
• "Domain growth in the Heisenberg ferromagnet: Effective vector theory of the S=1/2 model", V. M. Turkowski, P. D. Sacramento and V. R. Vieira, Phys. Rev. B 73, 214437 (2006).
• "Current-induced motion of a domain wall in magnetic nanowires", V. K. Dugaev, V. R. Vieira, P. D. Sacramento, J. Barnas, M. A. N. Araújo and J. Berakdar, Physical Review B (2006).

Preprints

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Curriculum Vitae

Short Curriculum Vitae