Electro-Mechanical Response of Top-Gated LaAlO3/SrTiO3 Heterostructures

TL;DR

This study investigates the electromechanical behavior of top-gated LaAlO3/SrTiO3 heterostructures, revealing nanoscale conducting islands and their role in the hysteretic metal-insulator transition through combined PFM and capacitance spectroscopy.

Contribution

It provides new insights into the physical origin of the hysteretic MIT by correlating local electromechanical variations with capacitance dynamics.

Findings

Local hysteretic responses vary across the heterostructure

Enhanced capacitance is linked to nanoscale conducting islands

Charging/discharging dynamics explain the MIT behavior

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: piezoforce microscopy (PFM) and capacitance spectroscopy. PFM measurements reveal local variations in the hysteretic response, which is directly correlated with 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.