Antisymmetric magnetoresistance of the SrTiO3/LaAlO3 interface

The longitudinal resistance $R_{xx}$ of the SrTiO3/LaAlO3 interface with magnetic fields applied perpendicular to the interface has an antisymmetric term (namely, $R_{xx}(H)\neq R_{xx}(-H)$) which increases with decreasing temperature and increasing field. We argue that the origin of this phenomenon is a non-homogeneous Hall effect with clear contribution of an extraordinary Hall effect, suggesting the presence of non-uniform field-induced magnetization.