Channel-like conduction in LaAlO$_3$/SrTiO$_3$ heterointerfaces

LaAlO$_3$/SrTiO$_3$ (LAO/STO) heterostructures exhibit metallic conduction at the interface. Many studies of LAO/STO properties are done by transport measurements which measure conductance over macroscopic areas of the sample or device. Local information about the electronic transport is crucial to the understanding of such new materials. We use scanning SQUID microscopy to map the magnetic field locally generated by current flowing at the interface in several LAO/STO samples. We find that the conduction is non-homogeneous and channel-like on the scale of microns and that the stripes/channels are related to tetragonal domains formed in the STO below $\sim$ 105K. We will describe the details of this exciting observation and its impact on transport studies of the LAO/STO interface.