Anomalous transport proper.es of SrTiO3 (STO) accumula.on layers

Abstract

In this talk, we study the low temperature conductivity of electron accumulation layers induced by the very strong electric field at the surface of STO sample. Due to the strongly nonlinear lattice dielectric response, the three-dimensional density of electrons n(z) in such a layer decays with the distance from the surface z very slowly as n(z)~1/z^{12/7}. We show that when the mobility is limited by the surface scattering, the contribution of such a tail to the conductivity diverges at large z because of growing time electrons need to reach the surface. We explore truncation of this divergence by the finite sample width, by the bulk scattering rate, or by the crossover to the bulk linear dielectric response with the dielectric constant \kappa. As a result we arrive at the anomalously large mobility, which depends not only on the rate of the surface scattering, but also on the physics of truncation. Similar anomalous behavior is found for the Hall factor, the magnetoresistance, and the thermopower.