Current-driven magnetization switching in ferromagnetic bulk Rashba semiconductor (Ge,Mn)Te

Yoshimi, Ryutaro; Yasuda, K.; Tsukazaki, Atsushi; Takahashi, Kei; Kawasaki, Masashi; Tokura, Y.

doi:10.1126/sciadv.aat9989

Cited by 33 publications

(40 citation statements)

References 40 publications

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“…The Rashba model for a 2DEG is easily extended to three dimensions, in order to cover multiferroic Rashba semiconductors with bulk Rashba SOC, an example being like (GeMn)Te [88][89][90]. In equilibrium, the magnetization of (GeMn)Te is parallel to the direction of the ferroelectric polarization [88]; it is conceivable that an in-plane field causes considerable in-plane canting and a MSHE.…”

Section: Effect Of Hexagonal Warpingmentioning

confidence: 99%

Origin of the magnetic spin Hall effect: Spin current vorticity in the Fermi sea

Mook

Neumann

Johansson

et al. 2020

Phys. Rev. Research

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The interplay of spin-orbit coupling (SOC) and magnetism gives rise to a plethora of charge-to-spin conversion phenomena that harbor great potential for spintronics applications. In addition to the spin Hall effect, magnets may exhibit a magnetic spin Hall effect (MSHE), as was recently discovered [Kimata et al., Nature 565, 627-630 (2019)]. To date, the MSHE is still awaiting its intuitive explanation. Here we relate the MSHE to the vorticity of spin currents in the Fermi sea, which explains pictorially the origin of the MSHE. For all magnetic Laue groups that allow for nonzero spin current vorticities the related tensor elements of the MSH conductivity are given. Minimal requirements for the occurrence of a MSHE are compatibility with either a magnetization or a magnetic toroidal quadrupole. This finding implies in particular that the MSHE is expected in all ferromagnets with sufficiently large SOC. To substantiate our symmetry analysis, we present various models, in particular a two-dimensional magnetized Rashba electron gas, that corroborate an interpretation by means of spin current vortices. Considering thermally induced spin transport and the magnetic spin Nernst effect in magnetic insulators, which are brought about by magnons, our findings for electron transport can be carried over to the realm of spincaloritronics, heat-to-spin conversion, and energy harvesting. I. FROM THE CONVENTIONAL TO THE MAGNETIC SPIN HALL EFFECTThe spin Hall effect (SHE) [1] and its inverse are without doubt important discoveries [2][3][4][5][6] in the field of spintronics [7,8]. They serve not only as 'working horses' for generating and detecting spin currents [9] but also as key ingredients in spin-orbit torque devices for electric magnetization switching [10][11][12]. Compared to spin-transfer torque devices [13-17], spin-orbit torque devices are faster, more robust, and consume less power upon operation [18][19][20]; for a recent review see Ref. 21. While the anomalous Hall effect (AHE) in a magnet [22] produces a transverse charge current density upon applying an electric field E, the SHE in a nonmagnet produces a transverse spin current density j γ = σ γ E (γ = x, y, z indicates the transported spin component). Mathematically, the SHE is quantified by the antisymmetric part of the spin conductivity tensor σ γ . For example, the σ z xy element comprises z-polarized spin currents in x direction as a response to an electric field in y direction.In a simple picture, the intrinsic SHE [23,24] is explained by spinning electrons that experience a spin-dependent Magnus force caused by spin-orbit coupling (SOC). It appears as if 'built-in' spin-dependent magnetic fields evoke spin-dependent Lorentz forces that result in a transverse pure spin current. The extrinsic SHE [25][26][27] is covered by Mott scattering at defects [28].Since the SHE does not rely on broken time-reversal symmetry (TRS), it is featured in nonmagnetic metals [29] or semiconductors [2]. Imposing few demands on a material's properties, a SHE can be expected in...

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Section: Effect Of Hexagonal Warpingmentioning

confidence: 99%

Origin of the magnetic spin Hall effect: Spin current vorticity in the Fermi sea

Mook

Neumann

Johansson

et al. 2020

Phys. Rev. Research

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“…Second, 0 increases as the Fe0.29TaS2 thickness increases, and is obtained to be (53. [25]), as shown in previous reports on (Ge, Mn)Te and Mn1.5Ga [52,53]. Hence, the intrinsic anomalous Hall mechanism provides a unique experimental method to probe the Berry curvaturerelated physics for the emergent 2D ferromagnetic materials [8,9].…”

Section: Discussionmentioning

confidence: 52%

“…𝛽 0 exhibits some variation as the Fe0.29TaS2 thickness changes, which might be due to different Berry curvature associated with different Fermi level positions evidenced by thickness-dependent carrier density (Fig. S9 in Supplemental Material [25]), as shown in previous reports on (Ge, Mn)Te and Mn1.5Ga [52,53]. Hence, the intrinsic anomalous Hall mechanism provides a unique experimental method to probe the Berry curvaturerelated physics for the emergent 2D ferromagnetic materials [8,9].…”

Section: Discussionmentioning

confidence: 54%

Anomalous Hall effect mechanisms in the quasi-two-dimensional van der Waals ferromagnet Fe0.29TaS2

et al. 2019

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The recent emergence of two-dimensional (2D) van der Waals ferromagnets has provided a new platform for exploring magnetism in the flatland and for designing 2D ferromagnet-based spintronics devices. Despite intensive studies, the anomalous Hall effect (AHE) mechanisms in 2D van der Waals ferromagnets have not been investigated yet. In this paper, we report the AHE mechanisms in quasi-2D van der Waals ferromagnet Fe0.29TaS2 via systematically measuring Fe0.29TaS2 devices with thickness from 14 nm to bulk single crystal. The AHE mechanisms are investigated via the scaling relationship between the anomalous Hall and channel conductivities.As the Fe0.29TaS2 thickness decreases, the major AHE mechanism changes from extrinsic

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“…Broken inversion symmetry in bulk states of the thin film is detected by optical SHG measurement for those high 11 mobility samples, suggesting the possible emergence of polar semimetal states with bulk gap closing. The versatile electronic states in such telluride based topological materials will lead to the emergent phenomena such as topological superconductivity and anomalous Hall effect, in particular when they are proximitized with each other in a form of heterostructure [10,12,29].…”

Section: Main Textmentioning

confidence: 99%

Versatile electronic states in epitaxial thin films of (Sn-Pb-In)Te: From topological crystalline insulator and polar semimetal to superconductor

Yoshimi

Masuko

Ogawa

et al. 2021

Phys. Rev. Materials

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Epitaxial thin films of (SnxPb1-x)1-yInyTe were successfully grown by molecular-beam-epitaxy (MBE) in a broad range of compositions (0 ≤ x ≤ 1, 0 ≤ y ≤0.23). We investigated electronic phases of the films by the measurements of electrical transport and optical second harmonic generation. In this system, one can control the inversion of band gap, the electric polarization that breaks the inversion symmetry, and the Fermi level position by tuning the Pb/Sn ratio and In composition. A plethora of topological electronic phases are expected to emerge, such as topological crystalline insulator, topological semimetal, and superconductivity. For the samples with large Sn compositions (x > 0.5), hole density increases with In composition (y), which results in the appearance of superconductivity. On the other hand, for those with small Sn compositions (x < 0.5), increase in In composition reduces the hole density and changes the carrier type from ptype to n-type. In a narrow region centered at (x, y) = (0.16, 0.07) where the n-type carriers are slightly doped, charge transport with high mobility exceeding 5,000 cm 2 V -1 s -1 shows up, representing the possible semimetal states. In those samples, the optical second harmonic generation measurement shows the breaking of inversion symmetry along the out-of-plane [111] direction, which ensures the presence of polar semimetal state. The thin films of (SnxPb1-x)1-yInyTe materials systems with a variety of electronic states would become a promising materials platform for the exploration of novel quantum phenomena.

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Current-driven magnetization switching in ferromagnetic bulk Rashba semiconductor (Ge,Mn)Te

Abstract: Current-driven switching of ferromagnetism is observed in a bulk material with Rashba-type spin-polarized band.

Cited by 33 publications

References 40 publications

Origin of the magnetic spin Hall effect: Spin current vorticity in the Fermi sea

Origin of the magnetic spin Hall effect: Spin current vorticity in the Fermi sea

Anomalous Hall effect mechanisms in the quasi-two-dimensional van der Waals ferromagnet Fe0.29TaS2

Versatile electronic states in epitaxial thin films of (Sn-Pb-In)Te: From topological crystalline insulator and polar semimetal to superconductor

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