Role of multiple subband renormalization in the electronic transport of correlated oxide superlattices

TL;DR

This paper investigates how multiple subband renormalization affects electronic transport in correlated oxide superlattices, emphasizing quantum confinement and electron-electron interactions, with implications for optical and thermoelectric properties.

Contribution

It introduces a self-consistent calculation of quasi-particle dispersion considering subband renormalization in oxide superlattices using slave-boson mean-field theory.

Findings

Renormalization significantly alters the quasi-particle dispersion.

Strong correlations impact optical conductivity and thermoelectric effects.

Subband structure influences metallic behavior at interfaces.

Abstract

Metallic behavior of band-insulator/ Mott-insulator interfaces was observed in artificial perovskite superlattices such as in nanoscale SrTiO3/LaTiO3 multilayers. Applying a semiclassical perspective to the parallel electronic transport we identify two major ingredients relevant for such systems: i) the quantum confinement of the conduction electrons (superlattice modulation) leads to a complex, quasi-two dimensional subband structure with both hole- and electron-like Fermi surfaces. ii) strong electron-electron interaction requires a substantial renormalization of the quasi-particle dispersion. We characterize this renormalization by two sets of parameters, namely, the quasi-particle weight and the induced particle-hole asymmetry of each partially filled subband. In our study, the quasi-particle dispersion is calculated self-consistently as function of microscopic parameters using the slave-boson mean-field approximation introduced by Kotliar and Ruckenstein. We discuss the consequences of strong local correlations on the normal-state free-carrier response in the optical conductivity and on the thermoelectric effects.