Effect of polar domain walls on macroscopic electrical properties at the (La,Sr)(Al,Ta)O3/SrTiO3 interfaces

The SrTiO3-based conducting heterointerfaces, when laterally confined by nanopatterning or defined using a conductive atomic force microscope, exhibit superior electronic properties compared to their macroscopic two-dimensional counterparts. This enhancement is attributed to the modulation of nanoscale transport properties by the polarity of SrTiO3 domain walls. However, the impact of polar domain walls on macroscopic electronic behavior remains poorly explored. In this study, we observe two distinct resistance anomalies at approximately 80 and 40 K, characteristic temperatures of SrTiO3 domain wall polarity, by measuring the macroscopic electrical transport properties of the (La0.3Sr0.7)(Al0.65Ta0.35)O3/SrTiO3 conducting heterointerface. As the carrier density decreases with decreasing gating voltage, these anomalies become more pronounced, with a metal-insulator-metal transition occurring near 40 K at a carrier density threshold of approximately 1 × 1012 cm−2. Our findings provide valuable insights into the role of polar domain walls in shaping the electronic characteristics of SrTiO3-based heterostructures and highlight the potential for manipulating macroscopic electronic behavior through domain wall engineering.