Persistent modification of magnetotransport properties in LaAlO3/SrTiO3 by gate-induced modification of structural domains

Abstract

We investigate the influence of large electric fields on the transport properties of nanostructures patterned into the electron gas at the interface between LaAlO3 and SrTiO3 (100). In these nanostructures, the transport is largely dominated by domain walls between structural domains in the SrTiO3 appearing below a structural phase transition temperature. We find that both positive and negative gate voltages applied in a side-gate configuration can induce persistent changes in the sample that are only reversed by warming through the phase transition. These changes include a resistance increase and a change in magnetoresistance in magnitude and sign. Furthermore, a resistance anomaly during warm-up that has been observed in the past can be further increased by briefly applying a side-gate voltage. These effects are typically observed in nanostructures below a certain size limit. The electric fields also increase this size limit from a few-hundred nm to more than 1 μm. All these observations can be consistently explained by a field-induced removal of specific domain-wall types accompanied by an increasing domain size and a reduced number of domain walls in the structures. The results not only show that under certain conditions domain walls can dominate the transport properties even of micron-sized structures, but they also provide an additional tuning knob to induce nonvolatile changes in the transport properties of LaAlO3/SrTiO3 interfaces at low temperatures.