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Electric field control of superconductivity at the LaAlO3/KTaO3(111) interface

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Science  14 May 2021:
Vol. 372, Issue 6543, pp. 721-724
DOI: 10.1126/science.abb3848

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Controlling interfacial superconductivity

The interface between the oxides LaAlO3 and KTaO3(111) has been shown to superconduct at temperatures up to 2 Kelvin. Chen et al. show that this superconductivity can be controlled with electric fields. As they tuned the gating voltage, the researchers observed a dome-shaped variation of the superconducting critical temperature. This variation could not be ascribed to the change in carrier density, but rather seemed to reflect the change in the mobility of the carriers.

Science, this issue p. 721

Abstract

The oxide interface between LaAlO3 and KTaO3(111) can harbor a superconducting state. We report that by applying a gate voltage (VG) across KTaO3, the interface can be continuously tuned from superconducting into insulating states, yielding a dome-shaped Tc-VG dependence, where Tc is the transition temperature. The electric gating has only a minor effect on carrier density but a strong one on mobility. We interpret the tuning of mobility in terms of change in the spatial profile of the carriers in the interface and hence, effective disorder. As the temperature is decreased, the resistance saturates at the lowest temperature on both superconducting and insulating sides, suggesting the emergence of a quantum metallic state associated with a failed superconductor and/or fragile insulator.

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