Dichotomy of the transport coefficients of correlated electron liquids in SrTiO3

TL;DR

This paper investigates the transport properties of correlated electrons in SrTiO3 quantum wells, revealing a dichotomy where some behaviors align with Fermi liquid theory while others do not, especially under strong correlations.

Contribution

It provides new insights into the transport behavior of correlated electron liquids, highlighting the breakdown of Fermi liquid assumptions in SrTiO3 quantum wells.

Findings

Seebeck coefficient increases linearly with temperature at high T

Mobility decreases proportional to T^2 at high T

Transport scattering rate is independent of Fermi energy

Abstract

We discuss the Seebeck coefficient and the Hall mobility of electrons confined in narrow SrTiO3 quantum wells as a function of the three-dimensional carrier density and temperature. The quantum wells contain a fixed sheet carrier density of ~ 7x10^14 cm^-2 and their thickness is varied. At high temperatures, both properties exhibit apparent Fermi liquid behavior. In particular, the Seebeck coefficient increases nearly linearly with temperature (T) when phonon drag contributions are minimized, while the mobility decreases proportional to T^2. Furthermore, the Seebeck coefficient scales inversely with the Fermi energy (decreasing quantum well thickness). In contrast, the transport scattering rate is independent of the Fermi energy, which is inconsistent with a Fermi liquid. At low temperatures, the Seebeck coefficient deviates from the linear temperature dependence for those electron liquids that exhibit a correlation-induced pseudogap, indicating a change in the energy dependence of the scattering rate. The implications for describing transport in strongly correlated materials are discussed.