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

Nature Materials volume 12, pages 1091–1095 (2013)Cite this article

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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 1, 2). Transport and other measurements in this system show a plethora of diverse physical phenomena3,4,5,6,7,8,9,10,11,12,13,14. 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.

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Figure 1: Scanning SQUID measurements of current in LAO/STO heterostructures.
Figure 2: Current in unpatterned LAO/STO flows in narrow paths.
Figure 3: Tetragonal domain structure of STO is the origin of narrow paths of enhanced conductivity.
Figure 4: Schematic twin boundaries and domains in the STO crystal structure in the tetragonal phase.

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Acknowledgements

We thank G. A. Sawatzky, N. Pavlenko, S. Ilani, Y. Yacoby and A. Vailionis for discussions, Y. Yeshurun and E. Zeldov for use of their optical set-ups, J. Drori, D. Hadad and Y. Shperber for their assistance with the optical measurements and M. E. Huber for assistance in SQUID design and fabrication. S. Ilani and collaborators have performed complementary measurements by local electrostatic imaging. This work was primarily supported by the Department of Energy, Office of Basic Energy Sciences, Materials Sciences and Engineering Division, under contract DE-AC02-76SF00515. B.K. acknowledges support from FENA and the EC grant no. FP7-PEOPLE-2012-CIG-333799. Y.W.X. acknowledges partial support from the US Air Force Office of Scientific Research (FAQSSO-10-1-0524). J.M. acknowledges financial support by the German Science Foundation (TRR80).

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  1. Beena Kalisky and Eric M. Spanton: These authors contributed equally to this work

Authors and Affiliations

  1. Department of Applied Physics, Stanford University, Stanford, California 94305, USA

    Beena Kalisky, Hilary Noad, John R. Kirtley, Katja C. Nowack, Yanwu Xie, Harold Y. Hwang & Kathryn A. Moler

  2. Department of Physics, Nano-magnetism Research Center, Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 52900, Israel

    Beena Kalisky

  3. Department of Physics, Stanford University, Stanford, California 94305, USA

    Eric M. Spanton, Katja C. Nowack & Kathryn A. Moler

  4. Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA

    Eric M. Spanton, Hilary Noad, Christopher Bell, Hiroki K. Sato, Masayuki Hosoda, Yasuyuki Hikita, Harold Y. Hwang & Kathryn A. Moler

  5. Department of Advanced Materials Science, The University of Tokyo, Kashiwa, Chiba 277-8561, Japan

    Hiroki K. Sato & Masayuki Hosoda

  6. Max Planck Institute for Solid State Research, D-70569 Stuttgart, Germany

    Carsten Woltmann, Georg Pfanzelt & Jochen Mannhart

  7. Experimental Physics VI, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, D-86135 Augsburg, Germany

    Rainer Jany & Christoph Richter

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Contributions

B.K., E.M.S., H.N., J.R.K. and K.C.N. performed the SQUID measurements. B.K. performed polarized-light measurements. B.K., E.M.S. and J.R.K. analysed the data with input from K.A.M. C.B., H.K.S., Y.X., M.H. and Y.H. grew samples H1–H5. C.W., G.P. and R.J. grew samples M1 and M2. E.M.S., B.K. and K.A.M. prepared the manuscript with input from all co-authors. H.Y.H., J.M. and K.A.M. guided the work.

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Correspondence to Beena Kalisky or Kathryn A. Moler.

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Kalisky, B., Spanton, E., Noad, H. et al. Locally enhanced conductivity due to the tetragonal domain structure in LaAlO3/SrTiO3 heterointerfaces. Nature Mater 12, 1091–1095 (2013). https://doi.org/10.1038/nmat3753

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