Quantum oscillations from a two-dimensional electron gas at a Mott/band insulator interface

TL;DR

This study observes two-dimensional quantum oscillations in a Mott/band insulator heterojunction, revealing a small electron population with an effective mass of about 1 me, linked to interface t2g-states.

Contribution

It provides the first detailed magnetotransport analysis of quantum oscillations at a Mott/band insulator interface, highlighting the 2D nature and subband structure of the electron system.

Findings

Observation of Shubnikov-de Haas oscillations at the interface.

Identification of a small, 2D electron population with effective mass ~1 me.

Discussion of results in the context of SrTiO3 conduction band states.

Abstract

We report on the magnetotransport properties of a prototype Mott insulator/band insulator perovskite heterojunction in magnetic fields up to 31 T and at temperatures between 360 mK and 10 K. Shubnikov-de Haas oscillations in the magnetoresistance are observed. The oscillations are two-dimensional in nature and are interpreted as arising from either a single, spin-split subband or two subbands. In either case, the electron system that gives rise to the oscillations represents only a fraction of the electrons in the space charge layer at the interface. The temperature dependence of the oscillations are used to extract an effective mass of ~ 1 me for the subband(s). The results are discussed in the context of the t2g-states that form the bottom of the conduction band of SrTiO3.