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Phys. Rev. Lett. 80, 4261 - 4264 (1998)

Temperature-Frequency Scaling in Amorphous Niobium-Silicon near the Metal-Insulator Transition

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Hok-Ling Lee, John P. Carini, and David V. Baxter
Department of Physics, Indiana University, Bloomington, Indiana 47405

George Grüner
Department of Physics, University of California, Los Angeles, California 90024

Received 29 January 1998

Millimeter-wave transmission measurements have been performed in amorphous niobium-silicon alloy samples where the dc conductivity follows the critical temperature dependence σdc∝T1/2. The real part of the conductivity is obtained at eight frequencies in the range 87–1040 GHz for temperatures 2.6 K and above. In the quantum regime (ħω>kBT) the real part of the high-frequency conductivity has a power-law frequency dependence Re σ(ω)∝ω1/2. For temperatures 16 K and below the data exhibit temperature-frequency scaling predicted by theories of dynamics near quantum-critical points.


©1998 The American Physical Society

URL: http://link.aps.org/doi/10.1103/PhysRevLett.80.4261
DOI: 10.1103/PhysRevLett.80.4261
PACS: 72.15.Rn, 72.30.+q, 72.60.+g

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