Detailed transport investigation of the magnetic anisotropy of (Ga,Mn)As

Pappert, K.; Gould, C.; Sawicki, M.; Wenisch, J.; Βrunner, Karl; Schmidt, G.; Molenkamp, L. W.

doi:10.1088/1367-2630/9/9/354

Cited by 39 publications

(43 citation statements)

References 27 publications

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“…The K U1 term takes over the biaxial K C term with increasing temperature, and becomes dominant when temperature is close to the T C . 35 The contrasting difference between the ratios of anisotropy terms of the two systems may infer a difference in the origin of the anisotropies. However, the origin of the multiple uniaxial anisotropy terms in the bulk system ͑in this case, two terms͒ is not clear either.…”

Section: Discussionmentioning

confidence: 99%

Planar Hall effect and uniaxial in-plane magnetic anisotropy in Mnδ-dopedGaAs∕p−AlGaAs<

et al. 2008

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We have studied the planar Hall effect ͑PHE͒ in a Mn ␦-doped GaAs-based heterostructure consisting of Mn ␦-doped GaAs and p-type AlGaAs. We observe a distinct and large PHE and a specific in-plane ͓110͔ uniaxial magnetic anisotropy below the ferromagnetic transition temperature ͑T C ͒. This uniaxial in-plane magnetic anisotropy is found dominant over the biaxial cubic anisotropy, and is clearly identified by the angular dependence of PHE. This observation is quantitatively discussed in terms of two models of magnetization reversal: the coherent rotation model and the domain-wall motion model. The model calculation fit to the experimental data makes it possible to determine the uniaxial and cubic anisotropy fields and examine the behavior of magnetization reversal.

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Section: Discussionmentioning

confidence: 99%

Planar Hall effect and uniaxial in-plane magnetic anisotropy in Mnδ-dopedGaAs∕p−AlGaAs<

et al. 2008

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“…3, the DW nucleation/propagation energy ⑀ was equated with the gain in Zeeman energy during the reversal between the initial ͑M 0 ͒ and final ͑M 1 ͒ state of the magnetization in a constant field, ⑀ = H · ͑M 1 − M 0 ͒. 19 It has been previously shown 8 …”

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confidence: 99%

Complex domain-wall dynamics in compressively strainedGa1−xMnxAsepilayers

et al. 2008

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The domain-wall-induced reversal dynamics in compressively strained Ga 1−x Mn x As was studied employing the magneto-optical Kerr effect and Kerr microscopy. Due to the influence of a uniaxial part in the in-plane magnetic anisotropy 90°Ϯ ␦ domain walls with considerably different dynamic behavior are observed. While the 90°+ ␦ reversal is identified to be propagation dominated with a small number of domains, the case of 90°−␦ reversal involves a larger number of nucleation centers. The domain-wall nucleation/propagation energies ⑀ for both transitions are estimated using model calculations from which we conclude that single domain devices can be achievable using the 90°+ ␦ mode.The discovery of the ferromagnetic semiconductor Ga 1−x Mn x As and the possible implementation into spintronic devices triggered great interest in understanding its fundamental properties. 1 The linkage between carrier density and magnetic properties in this hole-mediated ferromagnet allows tuning of its magnetic properties such as the Curie temperature ͑T c ͒ upon changing the carrier concentration. 2,3 In addition, magnetic domain-wall ͑DW͒ logic operations may be implemented 4 including magnetoresistive read-outs. However, any application in this direction requires full control over magnetic reversal dynamics, which in most cases happens via the nucleation and propagation of domain walls.A good understanding of the magnetic anisotropy landscape is also required not only for the design of magnetoresistive devices but also because magnetic anisotropy can manifest in the domain-wall dynamics. The magnitude of the magnetic anisotropy is related to important parameters such as the domain-wall energy and width, 5 which can determine a process to be propagation or nucleation dominated. This can be very well visualized in the effect of a nonuniform anisotropy distribution in simulated reverse domain patterns. 6 So far, domain-wall studies by means of Kerr microscopy ͑KM͒ in Ga 1−x Mn x As have been mostly performed in films with tensile strain where the magnetization pointed perpendicular to the plane. 7 Ga 1−x Mn x As with in-plane magnetization has been extensively studied using magnetotransport measurements. 8,9 However, this technique does not provide spatially resolved information about DW nucleation and propagation processes. In this study we present the direct observation of DW motion in compressively strained Ga 1−x Mn x As by KM and the dependence of the DW dynamics on the direction of the applied magnetic field. While an earlier magneto-optical study in the literature 10 did not address possible anisotropies in the DW dynamics, our KM results reveal a distinct anisotropy in the DW dynamics dependent on the direction of the applied magnetic field with respect to the crystal axes. From the analysis of angleresolved magneto-optical Kerr effect ͑MOKE͒ measurements, we attribute this anisotropy to the existence of two different types of DWs. All measurements were done on Hall bar devices of 150 m width, patterned in ͓110͔ and ͓110͔ direc...

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“…This leads the position of energy minima slightly off from the 〈100〉 directions. The deviation angle,δ, of the magnetic easy axes from the 〈100〉 directions can be calculated by using the relation of anisotropy fields [26]:…”

Section: Resultsmentioning

confidence: 99%