Two-dimensional electron-gas-like charge transport at magnetic Heusler alloy-SrTiO$_3$ interface

TL;DR

This study demonstrates high-mobility, low-resistivity charge transport at the interface of magnetic Heusler alloys and SrTiO$_3$, driven by oxygen vacancies, with implications for spintronics.

Contribution

It reveals a novel two-dimensional electron-gas-like conduction at the Heusler alloy-SrTiO$_3$ interface due to oxygen vacancies, not observed on other substrates.

Findings

High mobility (~10^4 cm^2V^{-1}s^{-1}) charge transport at the interface.

Oxygen vacancies confined within 1.9 nm of the interface.

Resistivity scales with film thickness allowing interface conductance extraction.

Abstract

We report remarkably low residual resistivity, giant residual resistivity ratio, free-electron-like Hall resistivity and high mobility ($\approx$ 10$^4$ cm$^2$V$^{-1}$s$^{-1}$) charge transport in epitaxial films of Co$_2$MnSi and Co$_2$FeSi grown on (001) SrTiO$_3$. This unusual behavior is not observed in films deposited on other cubic oxide substrates of comparable lattice parameters. The scaling of the resistivity with thickness of the films allow extraction of interface conductance, which can be attributed to a layer of oxygen vacancies confined within 1.9 nm of the interface as revealed by atomically resolved electron microscopy and spectroscopy. The high mobility transport observed here at the interface of a fully spin polarized metal is potentially important for spintronics applications.