Transport properties of strongly correlated metals: A dynamical mean-field approach

Abstract

The temperature dependence of the transport properties of the metallic phase of a frustrated Hubbard model on the hypercubic lattice at half-filling is calculated. Dynamical mean-field theory, which maps the Hubbard model onto a single impurity Anderson model that is solved self-consistently, and becomes exact in the limit of large dimensionality, is used. As the temperature increases there is a smooth crossover from coherent Fermi liquid excitations at low temperatures to incoherent excitations at high temperatures. This crossover leads to a nonmonotonic temperature dependence for the resistance, thermopower, and Hall coefficient, unlike in conventional metals. The resistance smoothly increases from a quadratic temperature dependence at low temperatures to large values which can exceed the Mott-Ioffe-Regel value បa/e 2 ͑where a is a lattice constant͒ associated with mean free paths less than a lattice constant. Further signatures of the thermal destruction of quasiparticle excitations are a peak in the thermopower and the absence of a Drude peak in the optical conductivity. The results presented here are relevant to a wide range of strongly correlated metals, including transition metal oxides, strontium ruthenates, and organic metals.

Power-law dependence of the optical conductivity observed in the quantum spin-liquid compoundκ-(BEDT-TTF)2Cu2(CN)Elsässer1, Wu2, Dressel3 et al. 2012Phys. Rev. B

“…2,46,47 Recently two approaches were brought forward both based on a quarter-filled extended Hubbard model that includes the interaction V between molecules on the same but also different dimers. In general, within Hubbard-type models there is no contribution from spins to optics; however, besides single electron conductivity, singlets might form which move around leading to an additional contribution to the optical conductivity.…”

Antiferromagnetic spin fluctuations in the metallic phase of quasi-two-dimensional organic superconductors

“…8,[15][16][17]47 This suggests that these systems undergo a crossover from a bad metal regime for T Ͼ T 0 to a renormalized Fermi liquid below T 0 . However, we will show below ͑also see Fig.…”

“…Many features of the metallic phase agree well with the predictions of dynamical meanfield theory ͑DMFT͒ 14 which describes the crossover from a "bad metal" at high temperatures to a Fermi liquid as the temperature is lowered. [15][16][17] This crossover from incoherent to coherent intralayer 18 transport has been observed in a number of experiments such as resistivity, 17 thermopower, 15,19 and ultrasonic attenuation. 20,21 The existence of coherent quasiparticles is also apparent from the observed magnetic quantum oscillations at low temperatures in -͑ET͒ 2 X.…”

“…This regime is often referred to as the "bad metal". 8,15 Microscopically the bad metal is characterized by quasilocalized electrons and the absence of quasiparticles. This temperature dependence is similar to that for the single impurity Anderson model.…”

Ionic Hubbard model on a triangular lattice forNa0.5CoO2,Rb0.5Powell1, Merino2, McKenzie3 2009Phys. Rev. BSelf Cite9020View full textAdd to dashboardCite

“…For example, in many strongly correlated systems, such as the organic superconductors, 59 the charge transport is incoherent at high temperatures-this leads to a resistivity with a broad maximum slightly above the temperature where quasiparticle coherence is lost. 60 Above, we have shown that the slave boson theory of Hamiltonian ͑2͒ produces two bands. We will assume that some features of these bands survive even in the exact solution even if the simple single particle states of the slave boson theory do not.…”