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arXiv 0908.2935cond-mat.mtrl-sci
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(Ga,Mn)As反常霍尔效应的标度关系

Scaling relation of the anomalous Hall effect in (Ga,Mn)As

M. Glunk, J. Daeubler, W. Schoch, R. Sauer, W. Limmer

摘要:

我们目前的磁输运研究上进行的一组扩展的(Ga,Mn)作为样品在4.2 K的纵向电导率sigma_{xx}范围从低到高的导电率制度。从测量的纵向电导率和霍尔电导率中提取反常霍尔电导率sigma_{xy} ^(AH)。在高电导率区,由于Berry相效应,sigma_{xy} ^(AH)=20 Ω ^{-1}cm^{-1}转变为低电导率样品的比例关系sigma_{xy} ^(AH)与sigma_{xx} ^{1.6}成比例。这种标度关系是一致的,最近开发的统一理论的异常霍尔效应的框架内的Keldysh形式主义。它原来是独立的晶体取向,生长条件,锰浓度,和应变,因此可以被认为是普遍的低电导率(Ga,Mn)As。在低电导率(Ga,Mn)As中,从磁输运测量导出空穴浓度值时,该关系起着至关重要的作用。此外,高电导率样品的空穴扩散常数由测量的纵向电导率确定。

英文摘要:

We present magnetotransport studies performed on an extended set of (Ga,Mn)As samples at 4.2 K with longitudinal conductivities sigma_{xx} ranging from the low- to the high-conductivity regime. The anomalous Hall conductivity sigma_{xy}^(AH) is extracted from the measured longitudinal and Hall resistivities. A transition from sigma_{xy}^(AH)=20 Omega^{-1}cm^{-1} due to the Berry phase effect in the high-conductivity regime to a scaling relation sigma_{xy}^(AH) proportional to sigma_{xx}^{1.6} for low-conductivity samples is observed. This scaling relation is consistent with a recently developed unified theory of the anomalous Hall effect in the framework of the Keldysh formalism. It turns out to be independent of crystallographic orientation, growth conditions, Mn concentration, and strain, and can therefore be considered universal for low-conductivity (Ga,Mn)As. The relation plays a crucial role when deriving values of the hole concentration from magnetotransport measurements in low-conductivity (Ga,Mn)As. In addition, the hole diffusion constants for the high-conductivity samples are determined from the measured longitudinal conductivities.

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