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Effect of two-level systems on the spectral density of universal conductance fluctuations in doped Si

Ghosh, Arindam and Raychaudhuri, AK (2002) Effect of two-level systems on the spectral density of universal conductance fluctuations in doped Si. In: Physical Review B: Condensed Matter and Materials Physics, 65 (3). 033310 .

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Official URL: http://prb.aps.org/abstract/PRB/v65/i3/e033310

Abstract

We have studied the power spectral density [S(f) = gamma/f(alpha)] of universal conductance fluctuations (UCF's) in heavily doped single crystals of Si, when the scatterers themselves act as the primary source of dephasing. We observed that the scatterers, with internal dynamics like two-level-systems, produce a significant, temperature-dependent reduction in the spectral slope alpha when T less than or similar to 10 K, as compared to the bare 1/f (alphaapproximate to1) spectrum at higher temperatures. It is further shown that an upper cutoff frequency (f(m)) in the UCF spectrum is necessary in order to restrict the magnitude of conductance fluctuations, [(deltaG(phi))(2)], per phase coherent region (L-phi(3)) to [(deltaGphi)(2)](1/2) less than or similar to e(2)/h. We find that f(m) approximate to tau(D)(-1), where tau(D) = L-2/D, is the time scale of the diffusive motion of the electron along the active length (L) of the sample (D is the electron diffusivity).

Item Type: Journal Article
Additional Information: Copyright of this article belongs to The American Physical Society.
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 20 Jul 2011 08:25
Last Modified: 20 Jul 2011 08:25
URI: http://eprints.iisc.ernet.in/id/eprint/39159

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