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A high-mobility electron gas at the LaAlO3/SrTiO3 heterointerface

A Corrigendum to this article was published on 04 May 2006

Abstract

Polarity discontinuities at the interfaces between different crystalline materials (heterointerfaces) can lead to nontrivial local atomic and electronic structure, owing to the presence of dangling bonds and incomplete atomic coordinations1,2,3. These discontinuities often arise in naturally layered oxide structures, such as the superconducting copper oxides and ferroelectric titanates, as well as in artificial thin film oxide heterostructures such as manganite tunnel junctions4,5,6. If polarity discontinuities can be atomically controlled, unusual charge states that are inaccessible in bulk materials could be realized. Here we have examined a model interface between two insulating perovskite oxides—LaAlO3 and SrTiO3—in which we control the termination layer at the interface on an atomic scale. In the simple ionic limit, this interface presents an extra half electron or hole per two-dimensional unit cell, depending on the structure of the interface. The hole-doped interface is found to be insulating, whereas the electron-doped interface is conducting, with extremely high carrier mobility exceeding 10,000 cm2 V-1 s-1. At low temperature, dramatic magnetoresistance oscillations periodic with the inverse magnetic field are observed, indicating quantum transport. These results present a broad opportunity to tailor low-dimensional charge states by atomically engineered oxide heteroepitaxy.

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Figure 1: Growth and schematic models of the two possible interfaces between LaAlO3 and SrTiO3 in the (001) orientation.
Figure 2: Transport properties of the (LaO)+/(TiO2)0 interface for different oxygen partial pressures p O 2 during growth at 10-4, 10-5, and 10-6 torr, as well as for 10-6 torr growth followed by annealing in 1 atm of O2 at 400 °C for 2 h.
Figure 3: Low-temperature magnetoresistance of the (LaO)+/(TiO2)0 interface between 60-Å-thick LaAlO3 and SrTiO3 grown at 10-6 torr p O 2 .
Figure 4: The dependence of -1/RHe at 2 K on the p O 2 during growth for the samples in this study.

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Acknowledgements

We thank D. Schlom, D. R. Hamann and T. Ohnishi for discussions. We acknowledge partial support from NEDO's International Joint Research Program. A.O. acknowledges partial support from the Asahi Glass Foundation and the Inamori Foundation.

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Correspondence to H. Y. Hwang.

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Ohtomo, A., Hwang, H. A high-mobility electron gas at the LaAlO3/SrTiO3 heterointerface. Nature 427, 423–426 (2004). https://doi.org/10.1038/nature02308

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