Anisotropic electronic transport of the two-dimensional electron system in Al2O3/SrTiO3 heterostructures
AbstractTransport measurements on the two-dimensional electron system in Al2O3/SrTiO3 heterostructures indicate significant noncrystalline anisotropic behavior below T≈30K. 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.