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Electron Glass in Ultrathin Granular Al Films at Low Temperatures

E. Bielejec·Wenhao Wu
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Abstract

Quench-condensed granular Al films, with normal-state sheet resistance close to 10 k$Ω/\Box$, display strong hysteresis and ultraslow, non-exponential relaxation in the resistance when temperature is varied below 300 mK. The hysteresis is nonlinear and can be suppressed by a dc bias voltage. The relaxation time does not obey the Arrhenius form, indicating the existence of a broad distribution of low energy barriers. Furthermore, large resistance fluctuations, having a 1/f-type power spectrum with a low-frequency cut-off, are observed at low temperatures. With decreasing temperature, the amplitude of the fluctuation increases and the cut-off frequency decreases. These observations combine to provide a coherent picture that there exists a new glassy electron state in ultrathin granular Al films, with a growing correlation length at low temperatures.

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E. Bielejec, Wenhao Wu. 2001-10-23. Electron Glass in Ultrathin Granular Al Films at Low Temperatures. https://doi.org/10.1103/physrevlett.87.256601

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