"Locally enhanced conductivity due to the tetragonal domain structure in LaAlO3/SrTiO3 heterointerfaces"

Beena Kalisky: Eric M. Spanton, Hilary Noad, John R. Kirtley, Katja C. Nowack, Christopher Bell, Hiroki K. Sato, Masayuki Hosoda, Yanwu Xie, Yasuyuki Hikita, Carsten Woltmann, Georg Pfanzelt, Rainer Jany, Christoph Richter, Harold Y. Hwang, Jochen Mannhart & Kathryn A. Moler; Nature Materials, 09/08/13.

Additional Authors: Eric M. Spanton, Hilary Noad, John R. Kirtley, Katja C. Nowack, Christopher Bell, Hiroki K. Sato, Masayuki Hosoda, Yanwu Xie, Yasuyuki Hikita, Carsten Woltmann, Georg Pfanzelt, Rainer Jany, Christoph Richter, Harold Y. Hwang, Jochen Mannhart & Kathryn A. Moler

Abstract:

The ability to control materials properties through interface engineering is demonstrated by the appearance of conductivity at the interface of certain insulators, most famously the {001} interface of the band insulators LaAlO3 and TiO2-terminated SrTiO3 (STO; refs). Transport and other measurements in this system show a plethora of diverse physical phenomena To better understand the interface conductivity, we used scanning superconducting quantum interference device microscopy to image the magnetic field locally generated by current in an interface. At low temperature, we found that the current flowed in conductive narrow paths oriented along the crystallographic axes, embedded in a less conductive background. The configuration of these paths changed on thermal cycling above the STO cubic-to-tetragonal structural transition temperature, implying that the local conductivity is strongly modified by the STO tetragonal domain structure. The interplay between substrate domains and the interface provides an additional mechanism for understanding and controlling the behaviour of heterostructures.