Anisotropic electronic transport of the two-dimensional electron system in Al2O3/SrTiO3 heterostructures

TL;DR

This study investigates the anisotropic electronic transport properties of two-dimensional electron systems in Al2O3/SrTiO3 heterostructures, revealing defect-induced anisotropy, effects of magnetic fields, and differences in Rashba spin-orbit coupling compared to LaAlO3/SrTiO3.

Contribution

It provides new insights into the anisotropic transport mechanisms and spin-orbit interactions in Al2O3/SrTiO3 heterostructures, highlighting the role of defects and interfacial effects.

Findings

Significant noncrystalline anisotropic behavior below 30 K.

Defects like lattice dislocations influence anisotropic transport.

Rashba spin-orbit coupling is weaker than in LaAlO3/SrTiO3.

Abstract

Transport measurements on the two dimensional electron system in Al2O3 SrTiO3 heterostructures indicate significant noncrystalline anisotropic behavior below T = 30 K. Lattice dislocations in SrTiO3 and interfacial steps are suggested to be the main sources for electronic anisotropy. Anisotropic defect scattering likewise alters magnetoresistance at low temperature remarkably and influences spin-orbit coupling significantly by the Elliot Yafet mechanism of spin relaxation resulting in anisotropic weak localization. Applying a magnetic field parallel to the interface results in an additional field induced anisotropy of the conductance, which can be attributed to Rashba spin orbit interaction. Compared to LaAlO3 SrTiO3, Rashba coupling seems to be reduced indicating a weaker polarity in Al2O3 SrTiO3 heterostructures.