GaMnAs-based hybrid multiferroic memory device

Overby, M.; Чернышов, А. В.; Rokhinson, Leonid P.; Liu, X.; Furdyna, J. K.

doi:10.1063/1.2917481

Cited by 100 publications

(74 citation statements)

References 24 publications

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“…(Ga,Mn)As, epitaxially grown on (001) surface of GaAs, is compressively strained, which results in magnetization M lying in the plane of the layer perpendicular to the growth direction, with two easy axes along the [100] and [010] crystallographic directions [22,23]. Recently, control of magnetization via strain modulation has been demonstrated [24]. In this paper we use SO-generated polarization J E to…”

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confidence: 99%

Evidence for reversible control of magnetization in a ferromagnetic material by means of spin–orbit magnetic field

et al. 2009

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Conventional computer electronics creates a dichotomy between how information is processed and how it is stored. Silicon chips process information by controlling the flow of charge through a network of logic gates. This information is then stored, most commonly, by encoding it in the orientation of magnetic domains of a computer hard disk. The key obstacle to a more intimate integration of magnetic materials into devices and circuit processing information is a lack of efficient means to control their magnetization. This is usually achieved with an external magnetic field or by the injection of spin-polarized currents [1,2,3]. The latter can be significantly enhanced in materials whose ferromagnetic properties are mediated by charge carriers [4]. Among these materials, conductors lacking spatial inversion symmetry couple charge currents to spin by intrinsic spin-orbit (SO) interactions, inducing nonequilibrium spin polarization [5,6,7,8,9,10,11] tunable by local electric fields. Here we show that magnetization of a ferromagnet can be reversibly manipulated by the SO-induced polarization of carrier spins generated by unpolarized currents. Specifically, we demonstrate domain rotation and hysteretic switching of magnetization between two orthogonal easy axes in a model ferromagnetic semiconductor.In crystalline materials with inversion asymmetry, intrinsic spin-orbit interactions (SO) couple the electron spin with its momentumhk. The coupling is given by the Hamiltonian H so =h 2σ · Ω(k), whereh is the Planck's constant andσ is the electron spin operator (for holesσ should be replaced by the total angular momentum J). Electron states with different sign of the spin projection on Ω(k) are split in energy, analogous to the Zeeman splitting in an external magnetic field. In zinc-blende crystals such as GaAs there is a cubic Dresselhaus term[12] Ω D ∝ k 3 , while strain introduces a term Ω ε = C∆ε(k x , −k y , 0) that is linear in k, where ∆ε is the difference between strain in theẑ andx,ŷ directions [13]. In wurzite crystals or in multilayered materials with structural inversion asymmetry there also exists the Rashba term[14] Ω R which has a different symmetry with respect to the direction of k,, whereẑ is along the axis of reduced symmetry. In the presence of an electric field the electrons acquire an average momentumh∆k(E), which leads to the generation of an electric current j =ρ −1 E in the conductor, whereρ is the resistivity tensor. This current defines the preferential axis for spin precession Ω(j) . As a result, a nonequilibrium current-induced spin polarization J E Ω(j) is generated, whose magnitude J E depends on the strength of various mechanisms of momentum scattering and spin relaxation [5,15]. This spin polarization has been measured in non-magnetic semiconductors using optical [7,8,9,11,16] and electron spin resonance [17] techniques. It is convenient to parameterize J E in terms of an effective magnetic field H so . Different contributions to H so have different current dependencies (∝ j or j 3 ), as we...

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confidence: 99%

Evidence for reversible control of magnetization in a ferromagnetic material by means of spin–orbit magnetic field

et al. 2009

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“…12,13 Secondly, the strains measured in the two perpendicular in-plane directions have a same sign (which is opposite to that in the out-ofplane direction) and a very similar magnitude that confirms the biaxial character of this piezostressor. Finally, we investigated the consistency of the observed lattice distortions with that computed from the GaAs elastic constants 17 and lattice paramete1 8 . The in-plane and outof-plane lattice parameters of the investigated GaAs wafer measured while biasing the piezostressor at +150 V (see Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The magnitude of the out-of-plane lattice parameter was obtained from the diffraction along the sample normal, (004), direction. The magnitudes of the in-plane lattice parameters were obtained from diffractions containing the in-plane components of the diffraction vector [either (113) and (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13) or (115) and (1-15)]. …”

Section: Methodsmentioning

confidence: 99%

“…The strain measurements are routinely performed using the resistance strain gauges that are glued either to the piezo rod or to the investigated sample. 3,7,8 In this paper we report on a piezo-induced strain characterization by X-ray diffraction experiments where strains along all three directions -not only two as in the case of strain gauges -can be measured directly. We show that the piezo-induced strains in the lattice are strongly dependent on the wafer thickness and on the glue used to bond the sample to the piezoelectric actuator.…”

Section: Introductionmentioning

confidence: 99%

“…The use of single crystals or macroscopic piezo-actuator devices circumvents this issue and turned out to be a very useful in many material systems. [4][5][6][7] For example, in diluted magnetic semiconductors (DMS) -with a) Electronic mail: xaviermarti@berkeley.edu (Ga,Mn)As as a most well-known example -this method enabled the in situ control of magnetic anisotropy [7][8][9] and, consequently, the discovery of several new physical phenomena. In particular, the piezo-induced suppression of the temperature-related laser-pulse-induced precession of magnetization enabled us to observe the optical spin-transfer torque.…”

Section: Introductionmentioning

confidence: 99%

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Critical role of the sample preparation in experiments using piezoelectric actuators inducing uniaxial or biaxial strains

Butkovičová

Martí

Saidl

et al. 2013

Review of Scientific Instruments

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We report on a systematic study of the stress transferred from an electromechanical piezo-stack into GaAs wafers under a wide variety of experimental conditions. We show that the strains in the semiconductor lattice, which were monitored in situ by means of X-ray diffraction, are strongly dependent on both the wafer thickness and on the selection of the glue which is used to bond the wafer to the piezoelectric actuator. We have identified an optimal set of parameters that reproducibly transfers the largest distortions at room temperature. We have studied strains produced not only by the frequently used uniaxial piezostressors but also by the biaxial ones which replicate the routinely performed experiments using substrate-induced strains but with the advantage of a continuously tunable lattice distortion. The time evolution of the strain response and the sample tilting and/or bending are also analyzed and discussed.

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Electric‐Field Control of Magnetism in Ferromagnetic Semiconductors

Fukumura

2015

Spintronics for Next Generation Innovative Devices

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GaMnAs-based hybrid multiferroic memory device

Cited by 100 publications

References 24 publications

Evidence for reversible control of magnetization in a ferromagnetic material by means of spin–orbit magnetic field

Evidence for reversible control of magnetization in a ferromagnetic material by means of spin–orbit magnetic field

Critical role of the sample preparation in experiments using piezoelectric actuators inducing uniaxial or biaxial strains

Electric‐Field Control of Magnetism in Ferromagnetic Semiconductors

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