This article is cited in 3 papers

CONDENSED MATTER

Static and high-frequency hole transport in $p$-Si/SiGe heterostructures in the extreme quantum limit

I. L. Drichko^a, I. Yu. Smirnov^a, A. V. Suslov^b, Yu. M. Гальперин^acd, V. M. Vinokur^c, M. Mironov^e, O. A. Mironov<sup>fg

a</sup> Ioffe Physico-Technical Institute, Russian Academy of Sciences
^b National High Magnetic Field Laboratory, Florida State University
^c Argonne National Laboratory
^d Department of Physics and Center for Advanced Materials & Nanotechnology, University of Oslo
^e Musashi Institute of Technology
^f University of Warwick Science Park, Venture Centre
^g International Laboratory of High Magnetic Fields and Low Temperatures

Abstract: Complex high-frequency (HF), σ^AC = σ₁ − iσ₂, and static, σ^DC, conductivities, as well as current-voltage characteristics, have been measured in p-Si/SiGe heterostructures with a low hole density (p = 8.2 × 10¹⁰ cm⁻²) at temperatures T = 0.3–4.2 K in the ultraquantum limit, when the filling factor is v < 1. In order to determine the components of the HF conductivity, the acoustic contactless method in the “hybrid configuration” is used, when the surface acoustic wave propagates on the surface of the LiNbO₃ piezoelectric and the heterostructure is pressed to the surface by a spring. The conductivities σ₁ and σ₂ are determined from the damping and velocity of the surface acoustic waves that are measured simultaneously with varying the magnetic field. The revealed HF conductivity features—σ₁ ≫ |σ₂|, the negative sign of σ₂, the threshold behavior of the current-voltage characteristic, and the dependence I ∝ exp(-A/V ^0.3) in the subthreshold region—indicate the formation of a pinned Wigner crystal (glass) in the ultraquantum limit (T = 0.3–0.8 K, B > 14 T).

PACS: 73.23.-b, 73.43.-f, 73.50.Rb

Received: 14.06.2007

 English version: Journal of Experimental and Theoretical Physics Letters, 2007, 86:4, 244–248

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