Evidence for the Domain Wall Nature of Sketched LaAlO₃/SrTiO₃ Nanowires

The SrTiO₃ based complex oxide interfaces host a large array of tunable properties, which can be further programmed to a nanoscale by a conductive atomic force microscope (cAFM) probe. Stemming from the STO matrix, the quantum mechanical properties of cAFM enabled devices are drastically enhanced, with the origin remaining elusive. Here we investigate electrical and thermodynamical responses in cAFM sketched nanowires and reveal abnormal behaviors at temperature of 105 K, 80 K and 40 K, which are characteristic of the polar domain walls in STO.  Our evidence points to a ferroelastic domain wall nature of the cAFM nanowires, which is critical to understand the exotic correlated phenomena in cAFM devices.