Feng Bi, Mengchen Huang, Sangwoo Ryu, Sanghan Lee, Chang-Beom Eom, Jeremy Levy
LaAlO3/SrTiO3 heterostructures exhibit a sharp, hysteretic metal-insulator transition (MIT) with enhanced capacitance beyond the geometric limit. To understand the physical origin of this behavior, we investigate the electromechanical response of top-gated LaAlO3/SrTiO3 heterostructures using two simultaneous measurement techniques: piezoforce microscopy (PFM) and capacitance spectroscopy. PFM measurements reveal local variations in the hysteretic response, which is correlated with the capacitance measurements. The enhanced capacitance at the MIT is linked to charging/discharging dynamics of nanoscale conducting islands, which are revealed through PFM imaging and time-resolved capacitance and piezoresponse measurements.
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http://arxiv.org/abs/1302.0204
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