Spin Swapping Effect of Band Structure Origin in Centrosymmetric Ferromagnets

Park, Hyeon-Jong; Ko, Hye-Won; Go, Gyungchoon; Oh, Jung Hyun; Kim, Kyoung-Whan; Lee, Kyung Jin

doi:10.1103/physrevlett.129.037202

Cited by 12 publications

(4 citation statements)

References 66 publications

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“…The weak magnetization dependence of and rules out being derived from an OHE and rather further supports the spin-swapping mechanism. Note that it has been predicted theoretically that generated by spin swapping shows a weak magnetization dependence 28 , which we observe in our study.…”

Section: Resultssupporting

confidence: 84%

Generation of out-of-plane polarized spin current by spin swapping

et al. 2023

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The generation of spin currents and their application to the manipulation of magnetic states is fundamental to spintronics. Of particular interest are chiral antiferromagnets that exhibit properties typical of ferromagnetic materials even though they have negligible magnetization. Here, we report the generation of a robust spin current with both in-plane and out-of-plane spin polarization in epitaxial thin films of the chiral antiferromagnet Mn3Sn in proximity to permalloy thin layers. By employing temperature-dependent spin-torque ferromagnetic resonance, we find that the chiral antiferromagnetic structure of Mn3Sn is responsible for an in-plane polarized spin current that is generated from the interior of the Mn3Sn layer and whose temperature dependence follows that of this layer’s antiferromagnetic order. On the other hand, the out-of-plane polarized spin current is unrelated to the chiral antiferromagnetic structure and is instead the result of scattering from the Mn3Sn/permalloy interface. We substantiate the later conclusion by performing studies with several other non-magnetic metals all of which are found to exhibit out-of-plane polarized spin currents arising from the spin swapping effect.

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Section: Resultssupporting

confidence: 84%

Generation of out-of-plane polarized spin current by spin swapping

et al. 2023

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“…Note that the sign of OHC depends on the difference of E p and E s (or E t 2g ). While the previous models with phenomenological orbital texture parameter [19] cannot give an insight on the sign of OHC, our formalism clearly shows its direct connection to microscopic parameters. In addition, we remark that the sign of A determines whether the orbital texture is in the r-t type or the orbital Dresselhaus type and thus the sign of OHC depends on the geometrical type of the orbital texture.…”

Section: Application: Orbital Hall Conductivitymentioning

confidence: 72%

“…Also, through out this paper, we consider the dimensionless OAM operators (by dividing them by ). When t σ = t π , the Hamiltonian has the radial and tangential orbitals as its eigenstates, similar to the triangular lattice model while the radial orbital now becomes 3D, p r = kx p x + ky p y + kz p z , and two tangential bands are degenerate as previously studied in [7,19]. We can see the Hamiltonian is written in terms of the second-order products of the OAM operators, called the orbital angular position operators [13], as argued by symmetry analysis.…”

Section: Cubic Lattice With Spmentioning

confidence: 76%

Microscopic study of orbital textures

Han¹,

Lee²,

Kim³

2022

Preprint

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Many interesting spin and orbital transport phenomena originate from orbital textures, referring to kdependent orbital states. Most of previous works are based on symmetry analysis to model the orbital texture and analyze its consequences. However the microscopic origins of orbital texture and its strength are largely unexplored. In this work, we derive the orbital texture Hamiltonians from microscopic tight-binding models for various situations. To form an orbital texture, k-dependent hybridization of orbital states are necessary. We reveal two microscopic mechanisms for the hybridization: (i) lattice structure effect and (ii) mediation by other orbital states. By considering the orbital hybridization, we not only reproduce the orbital Hamiltonian obtained by the symmetry analysis but also reveal previously unreported orbital textures like orbital Dresselhaus texture and anisotropic orbital texture. The orbital Hamiltonians obtained here would be useful for analyzing the orbital physics and designing the materials suitable for spin-orbitronic applications. We show that our theory also provides useful microscopic insight into physical phenomena such as the orbital Rashba effect and the orbital Hall effect. Our formalism is so generalizable that one can apply it to obtain effective orbital Hamiltonians for arbitrary orbitals in the presence of periodic lattice structures.

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“…In this work, we demonstrate a field-free ultrafast SOT switching with CoFeB/Ti/CoFeB/MgO trilayers in which the top PMA CoFeB layer can be manipulated by spin currents generated from the bottom magnetic layer 25 or its interfaces 24 , 26 . An important difference of this trilayer from other field-free switching schemes is that spin polarizations carried by spin currents have both in-plane and out-of-plane components.…”

Section: Introductionmentioning

confidence: 99%

Field-free spin–orbit torque switching in ferromagnetic trilayers at sub-ns timescales

Yang,

Han,

Zhao

et al. 2024

Nat Commun

Self Cite

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Current-induced spin torques enable the electrical control of the magnetization with low energy consumption. Conventional magnetic random access memory (MRAM) devices rely on spin-transfer torque (STT), this however limits MRAM applications because of the nanoseconds incubation delay and associated endurance issues. A potential alternative to STT is spin-orbit torque (SOT). However, for practical, high-speed SOT devices, it must satisfy three conditions simultaneously, i.e., field-free switching at short current pulses, short incubation delay, and low switching current. Here, we demonstrate field-free SOT switching at sub-ns timescales in a CoFeB/Ti/CoFeB ferromagnetic trilayer, which satisfies all three conditions. In this trilayer, the bottom magnetic layer or its interface generates spin currents with polarizations in both in-plane and out-of-plane components. The in-plane component reduces the incubation time, while the out-of-plane component realizes field-free switching at a low current. Our results offer a field-free SOT solution for energy-efficient scalable MRAM applications.

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Spin Swapping Effect of Band Structure Origin in Centrosymmetric Ferromagnets

Cited by 12 publications

References 66 publications

Generation of out-of-plane polarized spin current by spin swapping

Generation of out-of-plane polarized spin current by spin swapping

Microscopic study of orbital textures

Field-free spin–orbit torque switching in ferromagnetic trilayers at sub-ns timescales

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