Repulsive versus attractive Hubbard model: Transport properties and spin-lattice relaxation rate

2014/12/31 by Rok Žitko, Rok Zitko, Žiga Osolin +3
Physics and Astronomy · #Condensed matter physics #Electrical resistivity and conductivity #Hubbard model #Magnetic field #Magnetization #Paramagnetism #Physics #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #Quantum mechanics #Quasiparticle #Seebeck coefficient #Superconductivity #Topological Materials and Phenomena #cond-mat.str-el

paper · pdf · doi:10.1103/physrevb.91.155111

published as Phys. Rev. B 91, 165116 (2015) · 19 pages, 20 figures. Final version

arxiv created 2015/04/03 · openalex publication_date 2015/04/08 · openalex created_date 2016/06/24 · arxiv updated 2017/10/02 · openalex updated_date 2026/08/05

Abstract

We contrast the transport properties (dc resistivity, Seebeck coefficient), optical conductivity, spectral functions, dynamical magnetic susceptibility, and the nuclear magnetic resonance 1/T₁ spin-lattice relaxation rate of the repulsive and attractive infinite-dimensional Hubbard models in the paramagnetic phase for a generic band filling. The calculations are performed in a wide temperature interval using the dynamical mean-field theory with the numerical renormalization group as the impurity solver. The attractive case exhibits significantly more complex temperature dependencies which can be explained by the behavior of the half-filled Hubbard model in external magnetic field with constant magnetization, to which the attractive Hubbard model maps through the partial particle-hole transformation. The resistivity is nonmonotonous for the strongly attractive case: it peaks significantly above the Mott-Ioffe-Regel value at a temperature T_max where the quasiparticle band disappears. For both signs of U we find particle-hole asymmetry in the self-energy at low energies, but with the opposite kind of excitations having longer lifetime. This leads to a strong suppression of the slope of the Seebeck coefficient in the attractive case rather than an enhancement as in the repulsive case. The spin-lattice relaxation rate in the strongly attractive case has a nonmonotonic temperature dependence, thereby revealing the pairing fluctuations.

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