Rashba-induced chirality switching of domain walls and suppression of the Walker breakdown

Stier, Martin; Creutzburg, Marcus; Thorwart, Michael

doi:10.1103/physrevb.90.014433

Cited by 13 publications

(16 citation statements)

References 31 publications

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“…In the past ten years, it has been predicted [4][5][6][7] and observed [8][9][10][11][12][13] that noncentrosymmetric magnets with large spin-orbit coupling can also exhibit large spin torque, a phenomenon called spin-orbit torques (SOT). The physics of SOT in homogeneous ferromagnets [14][15][16][17][18][19][20] and magnetic textures [21][22][23][24][25][26] has attracted a massive amount of attention since then. While these torques have been originally studied in bulk noncentrosymmetric magnets [8,9] and ultrathin magnetic multilayers [10][11][12][13], their observation has been recently extended to magnetic bilayers involving topological insulators [27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Spin-orbit torque in two-dimensional antiferromagnetic topological insulators

Ghosh

Manchon

2017

Phys. Rev. B

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We investigate spin transport in two-dimensional ferromagnetic (FTI) and antiferromagnetic (AFTI) topological insulators. In the presence of an in-plane magnetization AFTI supports zero energy modes, which enables topologically protected edge conduction at low energy. We address the nature of current-driven spin torque in these structures and study the impact of spin-independent disorder. Interestingly, upon strong disorder the spin torque develops an antidamping component (i.e., even upon magnetization reversal) along the edges, which could enable current-driven manipulation of the antiferromagnetic order parameter. This antidamping torque decreases when increasing the system size and when the system enters the trivial insulator regime.

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Section: Introductionmentioning

confidence: 99%

Spin-orbit torque in two-dimensional antiferromagnetic topological insulators

Ghosh

Manchon

2017

Phys. Rev. B

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“…The STT and the resulting nonadiabatic Rashba field-like STT are shown to become non-local in space for steep textures. The known results for broad Bloch DWs [27][28][29] are recovered as a limiting case. We calculate DW velocities for a broad range of widths of a Bloch DW and find a non-local nonadiabaticity parameter for steep textures.…”

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confidence: 87%

“…All terms of Eq. (2) can be expressed in terms ofĴ r , for which the Heisenberg equations of motion ∂ tĴr = − i Ĵ r , H − can readily be evaluated [27][28][29]. We find for the expectation value J r = Ĵ r…”

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confidence: 99%

Nonlocal spin torques in Rashba quantum wires with steep magnetic textures

Stier

Thorwart

2015

Phys. Rev. B

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We provide a general procedure to calculate the current-induced spin-transfer torque which acts on a general steep magnetic texture due to the exchange interaction with an applied spin-polarized current. As an example, we consider a one-dimensional ferromagnetic quantum wire and also include a Rashba spin-orbit interaction. The spin-transfer torque becomes generally spatially non-local. Likewise, the Rashba spin-orbit interaction induces a spatially nonlocal field-like nonequilibrium spin-transfer torque. We also find a spatially varying nonadiabaticity parameter and markedly different domain wall dynamics for very steep textures as compared to wide domain walls. PACS numbers: 75.78.Fg, 75.70.Tj, The exchange interaction of a spin-polarized electron current with localized magnetic moments in a ferromagnetic wire typically induces a spin transfer torque (STT). A pronounced consequence is the coordinated switching of the localized magnetic moments of a ferromagnetic domain wall (DW) in the wire generating a net DW motion [1][2][3]. Other magnetic textures also rose to recent prominence, such as magnetic vortices and skyrmions [4][5][6], or one-dimensional spin chains [7]. There, the magnetization changes on much shorter length scales as compared to the conventional broad mesoscopic Bloch domain walls. In addition, these textures are in general strongly affected by symmetry breaking interactions, such as the spin-orbit [8] or the Dzyaloshinskii-Moriya interaction [9,10]. Clearly, in small structures, the backaction of the local magnetic moments on the polarized itinerant electron spins can become relevant. In particular, they themselves experience a back-acting STT as well. For wide magnetic textures, the impact of backaction is generally small since the itinerant spins relax much faster than they have time to interact with the local moments. Hence, for wide textures, it is reasonable to assume a stationary spin polarized current which generates the (non-)adiabatic STT [11]. This assumption, however, becomes increasingly invalid in more narrow or steep magnetic textures. In this context, questions have been raised why the nonadiabaticity parameter β is much larger in small vortex structures [12,13] than compared to spin-waves in extended structures [14]. This effect has been traced back to a non-standard description of the STT [15]. For a unified description of the STT for arbitrary magnetic textures, several approaches have been developed [15][16][17][18][19][20][21][22]. Nevertheless, a complete picture is still missing. Spin relaxation has either been neglected [16,17] or included [18][19][20], quantum corrections are considered [23] or a semiclassical approach on the basis of spin diffusion has been formulated [15,24]. Spin-orbit interaction has been considered for broad textures [21,22] only. In this work, we provide a general and conceptually simple scheme to calculate the STT for arbitrary magnetic textures. To show the flexibility of the approach, we also include the Rashba spin-orbit interaction in the iti...

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“…Since the intial prediction of the above Rashba torques and subsequently verified experimentally [2,51], much studies on the SOT have been carried out in the past eight years in both homogeneous metallic ferromagnets [52,53,54,55,56,57,58,59,60] and magnetic textures [61,62,63,64,65,66,67,68,69,70]. In the following, we discuss an improved calculation of the Rashba spin torques.…”

Section: Current-induced Rashba Spin Torquesmentioning

confidence: 99%

Theory of Rashba Torques

Manchon

Zhang²

2017

Oxford Scholarship Online

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This chapter focuses on the theory of current-driven Rashba torque, a special type of spin–orbit mediated spin torque that requires broken spatial-inversion symmetry. This specific form of spin-orbit interaction enables the electrical generation of a non-equilibrium spin density that yields both damping-like and field-like torques on the local magnetic moments. We review the recent results obtained in (ferromagnetic and antiferromagnetic) two-dimensional electron gases, bulk magnetic semiconductors, and at the surface of topological insulators. We conclude by summarizing recent experimental results that support the emergence of Rashba torques in magnets lacking inversion symmetry.

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Rashba-induced chirality switching of domain walls and suppression of the Walker breakdown

Cited by 13 publications

References 31 publications

Spin-orbit torque in two-dimensional antiferromagnetic topological insulators

Spin-orbit torque in two-dimensional antiferromagnetic topological insulators

Nonlocal spin torques in Rashba quantum wires with steep magnetic textures

Theory of Rashba Torques

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