处于量子霍尔绝缘态的 SiGe 中二维空穴气的扩散热功率。

Diffusion thermopower of a two-dimensional hole gas in SiGe in a quantum Hall insulating state.

作者信息

Possanzini C, Fletcher R, Coleridge P T, Feng Y, Williams R L, Maan J C

机构信息

Research Institute for Materials, High Field Magnet Laboratory, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands.

出版信息

Phys Rev Lett. 2003 May 2;90(17):176601. doi: 10.1103/PhysRevLett.90.176601. Epub 2003 Apr 28.

DOI:10.1103/PhysRevLett.90.176601

PMID:12786087

Abstract

Both the temperature dependence of resistivity and thermopower of a two-dimensional hole gas in SiGe show a reentrant metal-insulator transition at filling factor nu=1.5, but with strikingly different behavior of the two coefficients. As the temperature is decreased in the insulating state, the resistivity diverges exponentially while the thermopower decreases rapidly, suggesting that the insulating state is due to the presence of a mobility edge rather than a gap at the Fermi energy.

摘要

硅锗中二维空穴气的电阻率和热电势的温度依赖性在填充因子ν = 1.5时均呈现出折返式金属-绝缘体转变，但这两个系数的行为却显著不同。在绝缘态下，随着温度降低，电阻率呈指数发散，而热电势迅速减小，这表明绝缘态是由于迁移率边的存在而非费米能处的能隙所致。