Imaging and tuning polarity at SrTiO3 domain walls

TL;DR

This paper demonstrates that SrTiO3 domain walls can be polarized and tuned using localized pressure, affecting the LaAlO3/SrTiO3 interface conductivity, and offering a new way to manipulate oxide-based nanoscale devices.

Contribution

It provides direct evidence of polarity at SrTiO3 twin boundaries and shows they can be used as tunable gates to control interface properties.

Findings

SrTiO3 domain walls are highly mobile at low temperatures.

Applying localized pressure changes interface current distribution.

Domain boundaries can serve as effective, tunable gates.

Abstract

Electrostatic fields tune the ground state of interfaces between complex oxide materials. Electronic properties, such as conductivity and superconductivity, can be tuned and then used to create and control circuit elements and gate-defined devices. Here we show that naturally occurring twin boundaries, with properties that are different from their surrounding bulk, can tune the LaAlO3/SrTiO3 interface 2DEG at the nanoscale. In particular, SrTiO3 domain boundaries have the unusual distinction of remaining highly mobile down to low temperatures, and were recently suggested to be polar. Here we apply localized pressure to an individual SrTiO3 twin boundary and detect a change in LaAlO3/SrTiO3 interface current distribution. Our data directly confirm the existence of polarity at the twin boundaries, and demonstrate that they can serve as effective tunable gates. As the location of SrTiO3 domain walls can be controlled using external field stimuli, our findings suggest a novel approach to manipulate SrTiO3-based devices on the nanoscale.