Fachgruppe Nanostrukturierte Materialien    

A number of recent studies indicate that the charge conduction of the LaAlO3/SrTiO3 interface at low temperature is confined to filaments which are linked to structural domain walls in SrTiO3 with drastic con- sequences, for example, for the temperature dependence of local transport properties. We demonstrate that as a consequence of these current carrying filaments, on the nano-scale the magnetotransport properties of the interface are highly anisotropic. Our magnetoresistance measurements reveal that the magnetoresistance in different nanostructures (< 500 nm) is random in magnitude and sign. Warming up nanostructures above the structural phase transition temperature (105 K) results in a significant change in magnetoresistance. Even a sign change of the magnetoresistance is possible. The results suggest that domain walls that are differently oriented with respect to the surface exhibit different respective magnetoresistances and the total magnetoresistance is a result of a random domain wall pattern formed during the structural phase transition in SrTiO3 at cooldown.