Orbital torque in magnetic bilayers

Lee, Dongjoon; Go, Dongwook; Park, Hyeon-Jong; Jeong, Wonmin; Ko, Hye-Won; Yun, Deokhyun; Jo, Daegeun; Lee, Soogil; Go, Gyungchoon; Oh, Jung Hyun; Kim, Kab‐Jin; Park, Byong‐Guk; Min, Byoung‐Chul; Koo, Hyun Cheol; Lee, Hyun Woo; Lee, OukJae; Lee, Kyung Jin

doi:10.21203/rs.3.rs-509141/v1

Cited by 8 publications

(16 citation statements)

References 41 publications

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“…Since η FM originates from the spin-orbit coupling, or more precisely the spin-orbit correlation near the Fermi energy, in the FM layer 22 , the orbital torque is sensitive to the electronic structure of the FM layer 21 . Among the conventional 3d FMs, Ni is predicted to have the strongest spin-orbit correlation near the Fermi energy 31 . The strong spin-orbit correlation in Ni is consistent with it's strong spin and anomalous Hall effects, transport phenomena that also arise from the spin-orbit coupling 35,36…”

Section: Evidence and Characteristics Of Orbital Transportmentioning

confidence: 99%

“…In the FMs, the angular momentum of the injected spin and orbital currents is transferred to the local spins, giving rise to torques on the magnetization: spin and orbital torques 22 . Recent experimental studies have suggested the presence of the current-induced orbital torque [25][26][27][28][29][30][31][32][33] . However, the observed torque efficiency is much lower than the spin counterpart despite the fundamental role of the orbital response in the angular momentum transport.…”

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confidence: 99%

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Observation of long-range orbital transport and giant orbital torque

Hayashi¹,

Jo²,

Go³

et al. 2022

Preprint

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Modern spintronics relies on the generation of spin currents through spin-orbit coupling. The spin-current generation has been believed to be triggered by current-induced orbital dynamics, which governs the angular momentum transfer from the lattice to the electrons in solids. The fundamental role of the orbital response in the angular momentum dynamics suggests the importance of the orbital counterpart of spin currents: orbital currents. However, evidence for its existence has been elusive. Here, we demonstrate the generation of giant orbital currents and uncover remarkable features of the orbital response. We experimentally and theoretically show that orbital currents propagate over longer distances than spin currents by more than an order of magnitude in a ferromagnet and nonmagnets. Furthermore, we find that the orbital current enables electric manipulation of magnetization with efficiencies significantly higher than the spin counterpart. These findings open the door to orbitronics that exploits orbital transport and spin-orbital coupled dynamics in solid-state devices. Main

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Section: Evidence and Characteristics Of Orbital Transportmentioning

confidence: 99%

mentioning

confidence: 99%

Observation of long-range orbital transport and giant orbital torque

Hayashi¹,

Jo²,

Go³

et al. 2022

Preprint

Self Cite

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“…The orbital current is similar to the spin current in many ways because both orbital angular momentum (OAM) and spin transform in the same way under symmetry operations. Thus, experiments so far have focused on light element systems where the spin current contribution is expected to be negligible [29][30][31][32][33][34], or systems where the orbital and spin currents compete with each other and are opposite in sign [33,35,36]. Although these experiments imply the presence of the orbital current, which can hardly be explained by the spin current picture, they are far from being "direct" confirmations of the orbital current.…”

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confidence: 99%

Long-Range Orbital Magnetoelectric Torque in Ferromagnets

Go¹,

Jo²,

Kim³

et al. 2021

Preprint

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“…As a surprise, recent studies accumulated evidence that the dynamics and transport of the orbital information can be released under the external stimuli such as electric field in many materials. Similar to those in spintronics, orbital current can carry the orbital angular moment originated from orbital Hall effect [494][495][496] and orbital Rashba effect [497][498][499][500][501], and exert torques on the magnetization. Hence, the orbitronics may provide another route to manipulate and detect magnetization.…”

Section: Orbital Angular Momentummentioning

confidence: 98%

Chirality as Generalized Spin-Orbit Interaction in Spintronics

Chen¹,

Luo²,

Bauer³

2022

Preprint

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Chirality or handedness is a digital relation between three vectors that distinguishes an object from its mirror image, such as the spread fingers of the right and left hand. The chirality of ground state magnetic textures defined by the vectors of magnetization, its gradient, and an electric field from broken inversion symmetry can be fixed by a strong relativistic spin-orbit interaction. This review focuses on the chirality observed in the excited states of the magnetic order, dielectrics, and conductors that hold transverse spins when they are evanescent. Even without any relativistic effect, the transverse spin of the evanescent waves are locked to the momentum and the surface normal of their propagation plane. This chirality thereby acts as a generalized spin-orbit interaction, which leads to the discovery of various chiral interactions between magnetic, phononic, electronic, photonic, and plasmonic excitations in spintronics that mediate the excitation of quasiparticles into a single direction, leading to phenomena such as chiral spin and phonon pumping, chiral spin Seebeck, spin skin, magnonic trap, magnon Doppler, and spin diode effects. Intriguing analogies with electric counterparts in the nano-optics and plasmonics exist. After a brief review of the concepts of chirality that characterize the ground state chiral magnetic textures and chirally coupled magnets in spintronics, we turn to the chiral phenomena of excited states. We present a unified electrodynamic picture for dynamical chirality in spintronics in terms of generalized spin-orbit interaction and compare it with that in nano-optics and plasmonics. Based on the general theory, we subsequently review the theoretical progress and experimental evidence of chiral interaction, as well as the near-field transfer of the transverse spins, between various excitations in magnetic, photonic, electronic and phononic nanostructures at GHz time scales. We provide a perspective for future research before concluding this article.

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Orbital torque in magnetic bilayers

Cited by 8 publications

References 41 publications

Observation of long-range orbital transport and giant orbital torque

Observation of long-range orbital transport and giant orbital torque

Long-Range Orbital Magnetoelectric Torque in Ferromagnets

Chirality as Generalized Spin-Orbit Interaction in Spintronics

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