Orbitally dominated Rashba-Edelstein effect in noncentrosymmetric antiferromagnets

Salemi, Leandro; Berritta, Marco; Nandy, Ashis; Oppeneer, Peter M.

doi:10.1038/s41467-019-13367-z

Cited by 81 publications

(41 citation statements)

References 54 publications

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“…It is well known that the Rashba state originates in a chiral orbital angular momentum texture [44][45][46]. Such an orbital Rashba effect persists even in the absence of spin-orbit coupling, which induces current-induced orbital dynamics and transport [47,48]. Through spin-orbit coupling, the orbital Rashba state couples to the spin and the spin texture emerges, thus leading to spin dynamics.…”

Section: Introductionmentioning

confidence: 99%

Theory of current-induced angular momentum transfer dynamics in spin-orbit coupled systems

Freimuth

Hanke

et al. 2020

Phys. Rev. Research

111

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Motivated by the importance of understanding various competing mechanisms to the current-induced spinorbit torque on magnetization in complex magnets, we develop a theory of current-induced spin-orbital coupled dynamics in magnetic heterostructures. The theory describes angular momentum transfer between different degrees of freedom in solids, e.g., the electron orbital and spin, the crystal lattice, and the magnetic order parameter. Based on the continuity equations for the spin and orbital angular momenta, we derive equations of motion that relate spin and orbital current fluxes and torques describing the transfer of angular momentum between different degrees of freedom, achieved in a steady state under an applied external electric field. We then propose a classification scheme for the mechanisms of the current-induced torque in magnetic bilayers. We evaluate the sources of torque using density functional theory, effectively capturing the impact of the electronic structure on these quantities. We apply our formalism to two different magnetic bilayers, Fe/W(110) and Ni/W(110), which are chosen such that the orbital and spin Hall effects in W have opposite sign and the resulting spin-and orbital-mediated torques can compete with each other. We find that while the spin torque arising from the spin Hall effect of W is the dominant mechanism of the current-induced torque in Fe/W(110), the dominant mechanism in Ni/W(110) is the orbital torque originating in the orbital Hall effect of the nonmagnetic substrate. Thus, the effective spin Hall angles for the total torque are negative and positive in the two systems. Our prediction can be experimentally identified in moderately clean samples, where intrinsic contributions dominate. This clearly demonstrates that our formalism is ideal for studying the angular momentum transfer dynamics in spin-orbit coupled systems as it goes beyond the "spin current picture" by naturally incorporating the spin and orbital degrees of freedom on an equal footing. Our calculations reveal that, in addition to the spin and orbital torque, other contributions such as the interfacial torque and self-induced anomalous torque within the ferromagnet are not negligible in both material systems.

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Section: Introductionmentioning

confidence: 99%

Theory of current-induced angular momentum transfer dynamics in spin-orbit coupled systems

Freimuth

Hanke

et al. 2020

Phys. Rev. Research

111

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“…The generated spin current can be transmitted into the adjacent FM layer, and the resulting torque can switch the magnetization of FM layer. [ 5,6,16–18 ]…”

Section: Introductionmentioning

confidence: 99%

“…The generated spin current can be transmitted into the adjacent FM layer, and the resulting torque can switch the magnetization of FM layer. [5,6,[16][17][18] magnetism, [33] and also which has the high magnetic moment of 8 μ B and it has a very capable for changing the properties of the material. [34] Furthermore, Gd posses very stable intermetallic phases such as PtGd, [35] which would have strong SHE that can be utilized as a spin current source to generate highly efficient SOT.…”

Section: Introductionmentioning

confidence: 99%

High‐Efficiency Spin–Orbit Torque Switching Using a Single Heavy‐Metal Alloy with Opposite Spin Hall Angles

Bekele

Liu

Cao

et al. 2020

Adv Elect Materials

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Spin–orbit torque (SOT) induced perpendicular magnetization switching in Pt1‐xGdx/Co/Al2O3 heterostructure with x = 0, 0.02, 0.14, 0.30, and 0.33 is investigated. With in‐plane charge current flowing through the Pt1‐xGdx layer, field‐free current‐induced magnetization switching is observed for all nonzero x due to the existence of opposite spin Hall angles (θSHA) from Pt1‐xGdx alloys. Furthermore, the large θSHA of about 0.27 is obtained in the optimal Pt0.70Gd0.30 alloy films, which is about four times larger than that of the pure Pt. This work suggests a simple and scalable method for realizing field‐free SOT switching, and provides potential candidates of spin Hall materials that can be used to produce highly efficient SOTs.

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“…LEE was first theoretically proposed [8] and then experimentally realized [9,10]. Recently, there has been growing interest in LEE [5,[11][12][13], and it was suggested that LEE can potentially switch the magnetic orderings of magnetic materials [5,13]. However, LEE only exists in metallic systems, and the electric field also generates a charge current (Ohm current).…”

Section: Introductionmentioning

confidence: 99%

Light-induced static magnetization: Nonlinear Edelstein effect

Zhou

Wang

et al. 2021

Phys. Rev. B

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Light can interact with magnetism in materials. Motivated by the Edelstein effect, whereby a static electric field can generate magnetization in metals, in this work we theoretically and computationally demonstrate that static magnetization can also be generated through light in semiconductors. Such an effect is essentially a second-order nonlinear response and can be considered as a generalization of the Edelstein effect. This nonlinear Edelstein effect (NLEE) applies to semiconductors under both linearly and circularly polarized light, and there are no constraints from either spatial inversion or time-reversal symmetry. With ab initio calculations, we reveal several prominent features of NLEE. We find that the light-induced orbital magnetizations can be significantly greater than the spin magnetizations, in contrast to standard intrinsic magnetism where the orbital magnetic moment is strongly quenched under crystal field. We show that in multilayer (multisublattice) materials, different ferromagnetic and ferrimagnetic structures can be realized under photon pumping, depending on the interlayer (intersublattice) symmetry. It is also possible to switch the magnetic ordering in antiferromagnetic materials. The relationship between NLEE and other magneto-optic effects, including the inverse Faraday effect and inverse Cotton-Mouton effect, is also discussed.

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Orbitally dominated Rashba-Edelstein effect in noncentrosymmetric antiferromagnets

Cited by 81 publications

References 54 publications

Theory of current-induced angular momentum transfer dynamics in spin-orbit coupled systems

Theory of current-induced angular momentum transfer dynamics in spin-orbit coupled systems

High‐Efficiency Spin–Orbit Torque Switching Using a Single Heavy‐Metal Alloy with Opposite Spin Hall Angles

Light-induced static magnetization: Nonlinear Edelstein effect

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