Anomalous Hall effect in ferromagnetic semiconductors with hopping transport

Allen, William; Gwinn, E. G.; Kreutz, T. C.; Gossard, A. C.

doi:10.1103/physrevb.70.125320

Cited by 31 publications

(37 citation statements)

References 28 publications

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“…Interestingly, even for the insulating (Ga,Mn)As samples with hopping transport as studied in Ref. 18 the scaling exponent γ turned out to be close to 0.4. Due to the fact that the scaling exponent α = 1.6, or equivalently γ = 0.4, has also been found in numerous other low-conductivity ferromagnets, independent of the details of the underlying transport process (see e.g.…”

Section: Resultsmentioning

confidence: 99%

“…11,12,13,14,15,16 Whereas most papers concerning the AHE in (Ga,Mn)As are primarily focused on the metallic regime 11,12,13,14,15,16 , only a few systematic studies concentrate on the low-conductivity regime. 13,17,18 Allen et al 18 examined the AHE in digitally doped (Ga,Mn)As structures with hopping transport on the insulating side of the metal insulator transition (MIT). Recently, Shen et al 17 focused on the lowconductivity regime of (Ga,Mn)As with ρ xx between 0.01 and 2 Ω cm.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2009

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We present magnetotransport studies performed on an extended set of (Ga,Mn)As samples at 4.2 K with longitudinal conductivities σxx ranging from the low-to the high-conductivity regime. The anomalous Hall conductivity σ (AH) xy is extracted from the measured longitudinal and Hall resistivities. A transition from σ (AH) xy = 20 Ω −1 cm −1 due to the Berry phase effect in the high-conductivity regime to a scaling relation σ (AH) xy ∝ σ 1.6 xx 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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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2009

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“…Usually, AHE is only observed in DMS samples with relatively small resistivities, 4,10,33,48 since experimentally it is very hard to distinguish the AHE signal from the large longitudinal resistance at low temperatures. 33,49,50 Generally, the Hall resistance can be expressed as R Hall = R OH + R AH = R 0 B +4MR S . The ordinary Hall resistance R OH and the anomalous Hall resistance R AH are proportional to the external field B and the magnetization, respectively.…”

Section: Transport Propertiesmentioning

confidence: 99%

“…51͒ and ͑Ga,Mn͒As. 33,50 A possible origin of this behavior can be understood by a model developed by Burkov and Balents, 24 which has been used to study the AHE in DMS materials such as MnGe ͑Ref. 37͒ and ͑Ga,Mn͒P.…”

Section: Transport Propertiesmentioning

confidence: 99%

“…24,50 Equation ͑2͒ shows that while the sign of R OH is fixed for E F throughout the impurity band, the sign of R AH is dependent on the logarithmic derivative of the density of states at E F . Therefore, R AH could have both positive and negative signs, depending on the location of E F with respect to the extremum of the density of states, e.g., the sign of R AH is determined by the slope of the density of states at E F .…”

Section: Transport Propertiesmentioning

confidence: 99%

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Microstructure, magnetic, and spin-dependent transport properties of (Zn,Cr)Te films fabricated by magnetron sputtering

et al. 2008

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Chromium doped zinc telluride thin films with various doping concentrations are fabricated by magnetron sputtering. These films are ferromagnetic and the Curie temperature increases with Cr concentration. X-ray diffraction, transmission electron microscopy, and magnetic circular dichroism characterizations show that the films are free of Cr 1−x Te x impurities and the ferromagnetism is intrinsic. The transport study shows that the resistivity and magnetoresistance are governed by variable range hopping at low temperatures. A negative magnetoresistance as large as −57% is observed at 5 K. The magnetoresistance and its temperature dependence can be well explained by a model involving an increase in the localization length of carriers with a magnetic field in the hopping region. An anomalous Hall effect is also observed and a possible origin of the sign difference between the anomalous Hall resistance and ordinary Hall resistance is discussed.

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Quantum Transport in Diluted Magnetic Semiconductors

Jaroszyński

2010

Introduction to the Physics of Diluted Magnetic Semiconductors

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Anomalous Hall effect in ferromagnetic semiconductors with hopping transport

Cited by 31 publications

References 28 publications

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

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

Microstructure, magnetic, and spin-dependent transport properties of (Zn,Cr)Te films fabricated by magnetron sputtering

Quantum Transport in Diluted Magnetic Semiconductors

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