Anisotropic magnetotransport of electron gases at SrTiO3 (111) and (110) surfaces with high mobility

TL;DR

This study investigates the anisotropic magnetotransport properties of high-mobility electron gases at SrTiO3 surfaces with different orientations, revealing symmetry-dependent features linked to spin-orbit textures and electronic structure.

Contribution

It provides the first detailed analysis of anisotropic magnetoresistance symmetries at various SrTiO3 surface orientations, highlighting the influence of crystal symmetry on electronic transport.

Findings

Observed 4-fold, 2-fold, and nearly 6-fold AMR symmetries for (001), (110), and (111) surfaces.

Identified symmetry-breaking transition from 6-fold to 2-fold in (111)-surfaces.

Demonstrated the correlation between electronic structure symmetry and transport behavior.

Abstract

Electron gases at the surfaces of (001), (110), and (111) oriented SrTiO3 (STO) have been created using Ar+-irradiation with fully metallic behavior and low-temperature-mobility as large as 5500 cm2V-1s-1, 1300 cm2V-1s-1 and 8600 cm2V-1s-1 for (001)-, (110)-, and (111)-surfaces, respectively. The in-plane anisotropic magnetoresistance (AMR) have been studied for the samples with the current along different crystal axis directions to subtract the Lorentz Force effect. The AMR shows features which coincide with the fixed orientations to the crystalline axes, with 4-fold, 2-fold and nearly-6-fold symmetries for (001)-, (110) and (111)-surfaces, respectively, independent of the current directions. These features are possibly caused by the polarization of spin orbit texture of the 2D Fermi surfaces. In addition, a 6-fold to 2-fold symmetry breaking for (111)-surfaces is observed. Our results demonstrate the effect of symmetry of two-dimensional electronic structure on the transport behaviors for the electron gases at STO surfaces.