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Measurements of the Complex Conductivity of NbxSi1-x Alloys on the Insulating Side of the Metal-Insulator Transition

Erik Helgren·George Grüner·Martin Ciofalo·David V. Baxter·John P. Carini
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Abstract

We have conducted temperature and frequency dependent transport measurements in amorphous Nb_x Si_{1-x} samples in the insulating regime. We find a temperature dependent dc conductivity consistent with variable range hopping in a Coulomb glass. The frequency dependent response in the millimeter-wave frequency range can be described by the expression $sigma(omega) \propto (-\imath omega)^alpha$ with the exponent somewhat smaller than one. Our ac results are not consistent with extant theories for the hopping transport.

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Erik Helgren, George Grüner, Martin Ciofalo, David V. Baxter, John P. Carini. 2002-07-16. Measurements of the Complex Conductivity of NbxSi1-x Alloys on the Insulating Side of the Metal-Insulator Transition. https://doi.org/10.1103/physrevlett.87.116602

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