\delta-doped LaAlO3-SrTiO3 interface: Electrical transport and characterization of the interface potential

TL;DR

This study explores how delta-doping LaAlO3-SrTiO3 interfaces with LaMnO3 affects electrical transport, revealing increased resistance and thermopower due to suppressed mobile electrons and enhanced entropy, supported by a theoretical model.

Contribution

It introduces a model to analyze carrier concentration and thermopower changes caused by delta-doping at the interface, highlighting the role of spin and orbital entropy.

Findings

Doping inhibits mobile electron formation at the interface.

Thermopower is significantly enhanced due to increased entropy.

Resistance increases markedly with delta-doping.

Abstract

Here we investigate LaAlO_3-SrTiO_3 heterostructure with\delta-doping of the interface by LaMnO_3 at less than one monolayer. This doping strongly inhibits the formation of mobile electron layer at the interface. This results in giant increase of the resistance and the thermopower of the heterostructure. Several aspects of this phenomena are investigated. A model to calculate the carrier concentration is presented and effect of doping and detailed temperature dependence is analyzed in terms of model parameters and the weak-scattering theory. The large enhancement of thermopower is attributed to the increased spin and orbital entropy originating from the LaMnO_3 mono-layer.