| Summary: | LaAlO _3 /SrTiO _3 -based two-dimensional electron gas (2DEG) has been extensively studied because of its intriguing physical properties and potential application prospect. However, seldom researches have related their extraordinary macroscopic transport phenomena to the microscopic domain structure of SrTiO _3 . This requires some unique technique like scanning superconducting quantum interference device (SQUID) microscopy. In this work, we developed a different 2DEG system at the interface of SrNbO _3 thin film and SrTiO _3 . Using only the electrical methods, we found a pronounced hysteresis behavior in the resistance versus temperature curves, marked by the appearance/disappearance of two resistance peaks in the heating/cooling process. In sharp contrast to the conventional gate effect, the resistance peak grows under positive electric biases applied to backgate with conducting interface being grounded. In addition, a weak light (0.04 mW, 405 nm) can completely eliminate the two resistance anomalies. After a systematic analysis, we attribute the resistance anomaly to the cubic-tetragonal transition of bulk SrTiO _3 and surface SrTiO _3 . The present work presents a promising demonstration to get mesoscopic information on oxide interface via transport behaviors.
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