  Magnetoresistance (MR) anisotropy in LaAlO3/SrTiO3 (LAO/STO) interfaces is
compared between samples prepared in high oxygen partial pressure (PO2) of 10-4
mbar exhibiting quasi-two-dimensional (quasi-2D) electron gas and low PO2 of
10-6 mbar exhibiting 3D conductivity. While MR of an order of magnitude larger
was observed in low PO2 samples compared to those of high PO2 samples, large MR
anisotropies were observed in both cases. The MR with the out-of-plane field is
always larger compared to the MR with in-plane field suggesting lower
dissipation of electrons from interface versus defect scattering. The quasi-2D
interfaces show a negative MR at low temperatures while the 3D interfaces show
positive MR for all temperatures. Furthermore, the angle relationship of MR
anisotropy for these two different cases and temperature dependence of in-plane
MR are also presented. Our study demonstrates that MR can be used to
distinguish the dimensionality of the charge transport and various (defect,
magnetic center, and interface boundary) scattering processes in this system.
