  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.
