Transport characterization of the magnetic anisotropy of (Ga,Mn)As

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

doi:10.1063/1.2437075

Cited by 46 publications

(46 citation statements)

References 9 publications

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“…33 TMR in GaMnAs MTJs has a characteristic feature of the in-plane magnetic-field angle dependence, which is induced by an in-plane magnetic anisotropy of GaMnAs mainly expressed by the sum of the two components: biaxial easy axes (along the [100] and [010] directions) and a uniaxial easy axis (along [110] or [1 10]). 36 GaMnAs MTJ with a paramagnetic AlMnAs tunneling barrier as a function of the magnetic-field direction in the plane. Here, before starting to measure TMR, a strong magnetic field of 1 T was applied in the direction opposite to the intended magnetic-field direction and then was reduced to zero.…”

Section: Basic Properties Of Tmr In Gamnas Mtjsmentioning

confidence: 99%

Recent progress in III-V based ferromagnetic semiconductors: Band structure, Fermi level, and tunneling transport

Tanaka

Ohya

Hai

2014

Applied Physics Reviews

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Spin-based electronics or spintronics is an emerging field, in which we try to utilize spin degrees of freedom as well as charge transport in materials and devices. While metal-based spin-devices, such as magnetic-field sensors and magnetoresistive random access memory using giant magnetoresistance and tunneling magnetoresistance, are already put to practical use, semiconductor-based spintronics has greater potential for expansion because of good compatibility with existing semiconductor technology. Many semiconductor-based spintronics devices with useful functionalities have been proposed and explored so far. To realize those devices and functionalities, we definitely need appropriate materials which have both the properties of semiconductors and ferromagnets. Ferromagnetic semiconductors (FMS), which are alloy semiconductors containing magnetic atoms such as Mn and Fe, are one of the most promising classes of materials for this purpose, and thus have been intensively studied for the past two decades. Here, we review the recent progress in the studies of the most prototypical III-V based FMS, p-type (GaMn)As, and its heterostructures with focus on tunneling transport, Fermi level, and bandstructure. Furthermore, we cover the properties of a new n-type FMS, (InFe)As, which shows electron-induced ferromagnetism. These FMS materials having zinc-blende crystal structure show excellent compatibility with well-developed III-V heterostructures and devices.

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Section: Basic Properties Of Tmr In Gamnas Mtjsmentioning

confidence: 99%

Recent progress in III-V based ferromagnetic semiconductors: Band structure, Fermi level, and tunneling transport

Tanaka

Ohya

Hai

2014

Applied Physics Reviews

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“…͑A weak uniaxial component along the main crystal axes ͓͑100͔/͓010͔͒ has also been detected. 45,46 ͒ The theoretical model used so far to describe the easy-axis reorientation between the in-plane and out-of-plane alignment, assuming the growth strain, can account only for the cubic in-plane anisotropy component. In this case we find two easy axes perpendicular to each other either along the main crystal axes or along the diagonals, depending on the Mn concentration and hole density, as shown in Fig.…”

Section: B In-plane Anisotropy: Competition Of Cubic and Uniaxial Comentioning

confidence: 99%

Magnetocrystalline anisotropies in (Ga,Mn)As: Systematic theoretical study and comparison with experiment

et al. 2009

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We present a theoretical survey of magnetocrystalline anisotropies in ͑Ga,Mn͒As epilayers and compare the calculations to available experimental data. Our model is based on an envelope function description of the valence-band holes and a spin representation for their kinetic-exchange interaction with localized electrons on Mn 2+ ions, treated in the mean-field approximation. For epilayers with growth-induced lattice-matching strains we study in-plane to out-of-plane easy-axis reorientations as a function of Mn local-moment concentration, hole concentration, and temperature. Next we focus on the competition of in-plane cubic and uniaxial anisotropies. We add an in-plane shear strain to the effective Hamiltonian in order to capture measured data in bare unpatterned epilayers, and we provide microscopic justification for this approach. The model is then extended by an in-plane uniaxial strain and used to directly describe experiments with strains controlled by post-growth lithography or attaching a piezostressor. The calculated easy-axis directions and anisotropy fields are in semiquantitative agreement with experiment in a wide parameter range.

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“…The magnetization-reversal process for combined cubic and uniaxial anisotropies is sensitive to the specific anisotropy geometry and strength. 14,15 Depending on the field orientation, hysteresis curves with one and two steps are observed in various films and explained in terms of nucleation and propagation of 90°and 180°domain walls ͑DWs͒. 16,17 Additional information about the relevant reversal mechanisms has been obtained from microscopic imaging of the domain configuration.…”

Section: Introductionmentioning

confidence: 99%

Magnetic anisotropy and reversal in epitaxial Fe/MgO(001) films

et al. 2009

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We investigate the magnetization reversal in Fe/MgO͑001͒ films with fourfold in-plane magnetic anisotropy and an additional uniaxial anisotropy whose orientation and strength are altered using different growth geometries and postgrowth treatments. The previously adopted mechanism of 180°domain-wall nucleation clearly fails to explain the observed 180°magnetization reversal in Fe/MgO͑001͒ films. We introduce a reversal mechanism with two successive domain-wall nucleations to consistently predict the switching fields of Fe/ MgO͑001͒ films for all field orientations with one set of values for domain-wall nucleation energies and uniaxial anisotropy.

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Transport characterization of the magnetic anisotropy of (Ga,Mn)As

Cited by 46 publications

References 9 publications

Recent progress in III-V based ferromagnetic semiconductors: Band structure, Fermi level, and tunneling transport

Recent progress in III-V based ferromagnetic semiconductors: Band structure, Fermi level, and tunneling transport

Magnetocrystalline anisotropies in (Ga,Mn)As: Systematic theoretical study and comparison with experiment

Magnetic anisotropy and reversal in epitaxial Fe/MgO(001) films

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