Noninteger-spin magnonic excitations in untextured magnets

Kamra, Akashdeep; Agrawal, Utkarsh; Belzig, Wolfgang

doi:10.1103/physrevb.96.020411

Cited by 69 publications

(113 citation statements)

References 36 publications

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“…4(d), indicating that the magnon spin is suppressed due to ellipticity or "squeezing", which is in agreement with Ref. [61]. Without squeezing but nonzero DMI we identify spin-up and spin-down magnons by the antisymmetric blue-red features in Fig.…”

Section: Computer Experimentssupporting

confidence: 89%

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Magnonic analog of the Edelstein effect in antiferromagnetic insulators

Mook

Raeliarijaona

et al. 2020

Phys. Rev. B

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We investigate the nonequilibrium spin polarization due to a temperature gradient in antiferromagnetic insulators, which is the magnonic analogue of the inverse spin-galvanic effect of electrons. We derive a linear response theory of a temperature-gradient-induced spin polarization for collinear and noncollinear antiferromagnets, which comprises both extrinsic and intrinsic contributions. We apply our theory to several noncentrosymmetric antiferromagnetic insulators, i.e., to a one-dimensional antiferromagnetic spin chain, a single layer of kagome noncollinear antiferromagnet, e.g., KFe3(OH)6(SO4)2, and a noncollinear breathing pyrochlore antiferromagnet, e.g., LiGaCr4O8.

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Section: Computer Experimentssupporting

confidence: 89%

“…We choose γ ≤ 1 and λ ≥ 1, such that the collinear state with Néel vector along z direction is the classical magnetic ground state. For γ = 1, the anisotropy causes the magnons to experience the effect of "squeezing" [61].…”

Section: A Antiferromagnetic Spin Chainmentioning

confidence: 99%

Magnonic analog of the Edelstein effect in antiferromagnetic insulators

Mook

Raeliarijaona

et al. 2020

Phys. Rev. B

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“…. This ansatz implies an x-y-symmetry and thus vanishing in-plane anisotropy K ⊥ = K yy − K xx = 0 in order to avoid dealing with squeezed magnon states [79]. We assume a groundstate magnetization of m z A = +1 and m z B = −1.…”

Section: Appendix A: Dispersion Relation Of the Rocksalt-type Ferrimamentioning

confidence: 99%

“…We should note that we assumed a fixed magnon amplitude of in the derivation, which for the quantum mechanical case is a reasonable assumption for the FI [79], but seems arbitrary for the classical case [see Eq. (A14)].…”

Section: Appendix A: Dispersion Relation Of the Rocksalt-type Ferrimamentioning

confidence: 99%

Unveiling domain wall dynamics of ferrimagnets in thermal magnon currents: Competition of angular momentum transfer and entropic torque

Donges

Grimm

Jakobs

et al. 2020

Phys. Rev. Research

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Control of magnetic domain wall motion holds promise for efficient manipulation and transfer of magnetically stored information. Thermal magnon currents, generated by temperature gradients, can be used to move magnetic textures, from domain walls, to magnetic vortices and skyrmions. In the last years, theoretical studies have centered in ferro-and antiferromagnetic spin structures, where domain walls always move towards the hotter end of the thermal gradient. Here we perform numerical studies using atomistic spin dynamics simulations and complementary analytical calculations to derive an equation of motion for the domain wall velocity. We demonstrate that in ferrimagnets, domain wall motion under thermal magnon currents shows a much richer dynamics. Below the Walker breakdown, we find that the temperature gradient always pulls the domain wall towards the hot end by minimizating its free energy, in agreement with the observations for ferro-and antiferromagnets in the same regime. Above Walker breakdown, the ferrimagnetic domain wall can show the opposite, counterintuitive behavior of moving towards the cold end. We show that in this case, the motion to the hotter or the colder ends is driven by angular momentum transfer and therefore strongly related to the angular momentum compensation temperature, a unique property of ferrimagnets where the intrinsic angular momentum of the ferrimagnet is zero while the sublattice angular momentum remains finite. In particular, we find that below the compensation temperature the wall moves towards the cold end, whereas above it, towards the hot end. Moreover, we find that for ferrimagnets, there is a torque compensation temperature at which the domain wall dynamics shows similar characteristics to antiferromagnets, that is, quasi-inertia-free motion and the absence of Walker breakdown. This finding opens the door for fast control of magnetic domains as given by the antiferromagnetic character while conserving the advantage of ferromagnets in terms of measuring and control by conventional means such as magnetic fields. arXiv:1911.05393v1 [cond-mat.mtrl-sci]

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“…At very low temperature, there is a residual fluctuation due to the inter-sublattice coupling B ij in equation (3)[33,34].…”

mentioning

confidence: 99%

Finite temperature magnon spectra in yttrium iron garnet from a mean field approach in a tight-binding model

Shen

2018

New J. Phys.

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We study magnon spectra at finite temperature in yttrium iron garnet using a tight-binding model with nearest-neighbor exchange interaction. The spin reduction due to thermal magnon excitation is taken into account via the mean field approximation to the local spin and is found to be different at two sets of iron atoms. The resulting temperature dependence of the spin wave gap shows good agreement with experiment. We find that only two magnon modes are relevant to the ferromagnetic resonance.

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Noninteger-spin magnonic excitations in untextured magnets

Cited by 69 publications

References 36 publications

Magnonic analog of the Edelstein effect in antiferromagnetic insulators

Magnonic analog of the Edelstein effect in antiferromagnetic insulators

Unveiling domain wall dynamics of ferrimagnets in thermal magnon currents: Competition of angular momentum transfer and entropic torque

Finite temperature magnon spectra in yttrium iron garnet from a mean field approach in a tight-binding model

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