Electro-mechanical response of top-gated LaAlO3/SrTiO3

Abstract

LaAlO3/SrTiO3 heterostructures are known to exhibit a sharp, hysteretic metal-insulator transition (MIT) with large enhanced capacitance near depletion. To understand the physical origin of this behavior, the electromechanical response of top-gated LaAlO3/SrTiO3 heterostructures is probed using two simultaneous measurement techniques: piezoresponse force microscopy (PFM) and capacitance spectroscopy. The observed hysteretic PFM responses show strong correlation with the capacitance signals, suggesting an interfacial carrier-mediated structural distortion associated with the gate-tuned MIT. In addition, the frequency dependence of the capacitance enhancement in LaAlO3/SrTiO3 is found to be well-matched to local PFM measurements. Our experimental results provide a fuller understanding of the top-gate tuned MIT in oxide heterostructure, which could be helpful for the development of future oxide-based nanoelectronics.