Topological valley transport of gapped Dirac magnons in bilayer ferromagnetic insulators

Zhai, Xuechao; Blanter, Yaroslav M.

doi:10.1103/physrevb.102.075407

Cited by 18 publications

(7 citation statements)

References 60 publications

(162 reference statements)

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“…A non-trivial Berry curvature is also at the origin of the magnon valley transports that were recently reported in Ref. [45,46]. For the dipolar honeycomb lattice, a topological phase transition occurs at Ψ = 0 where the spin gap closes at the Dirac points and C V changes sign.…”

Section: Discussionsupporting

confidence: 63%

Dipolar spin-waves and tunable band gap at the Dirac points in the 2D magnet ErBr3

Wessler,

Roessli,

Krämer

et al. 2022

Preprint

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Topological magnon insulators constitute a growing field of research for their potential use as information carriers without heat dissipation. We report an experimental and theoretical study of the magnetic ground-state and excitations in the van der Waals two-dimensional honeycomb magnet ErBr 3 . We show that the magnetic properties of this compound are entirely governed by the dipolar interactions which generate a continuously degenerate non-collinear ground-state on the honeycomb lattice with spins confined in the plane. We find that the magnon dispersion exhibits Dirac-like cones when the magnetic moments in the ground-state are related by timereversal and inversion symmetries associated with a Berry phase π as in single-layer graphene. A magnon band gap opens when the dipoles are rotated away from this state, entailing a finite Berry curvature in the vicinity of the K and K' Dirac points.Our results illustrate that the spin-wave dispersion of dipoles on the honeycomb lattice can be reversibly controlled from a magnetic phase with Dirac cones to a topological antiferromagnetic insulator with non-trivial valley Chern number.

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Section: Discussionsupporting

confidence: 63%

Dipolar spin-waves and tunable band gap at the Dirac points in the 2D magnet ErBr3

Wessler,

Roessli,

Krämer

et al. 2022

Preprint

View full text Add to dashboard Cite

show abstract

“…A non-trivial Berry curvature is also at the origin of the magnon valley transports that were recently reported in refs. 45,46 . For the dipolar honeycomb lattice, a topological phase transition occurs at Ψ = 0 where the spin gap closes at the Dirac points and C V changes sign.…”

Section: Discussionmentioning

confidence: 99%

Dipolar spin-waves and tunable band gap at the Dirac points in the 2D magnet ErBr3

et al. 2022

View full text Add to dashboard Cite

Topological magnon insulators constitute a growing field of research for their potential use as information carriers without heat dissipation. We report an experimental and theoretical study of the magnetic ground-state and excitations in the van der Waals two-dimensional honeycomb magnet ErBr3. We show that the magnetic properties of this compound are entirely governed by the dipolar interactions which generate a continuously degenerate non-collinear ground-state on the honeycomb lattice with spins confined in the plane. We find that the magnon dispersion exhibits Dirac-like cones when the magnetic moments in the ground-state are related by time-reversal and inversion symmetries associated with a Berry phase π as in single-layer graphene. A magnon band gap opens when the dipoles are rotated away from this state, entailing a finite Berry curvature in the vicinity of the K and K’ Dirac points. Our results illustrate that the spin-wave dispersion of dipoles on the honeycomb lattice can be reversibly controlled from a magnetic phase with Dirac cones to a topological antiferromagnetic insulator with non-trivial valley Chern number.

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“…(i) Our considerations should apply to other magnonic systems, e.g., van der Waals heterostructures discussed in the context of magnon valleytronics [52][53][54]; vice versa, some of the effects from Refs. [52][53][54] could be transferred to BVDESWs.…”

Section: Discussionmentioning

confidence: 99%

Spin-wave wells revisited: From wavelength conversion and Möbius modes to magnon valleytronics

Fripp

Kruglyak

2021

Phys. Rev. B

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We have used micromagnetic simulations to model backward-volume dipole-exchange spin waves in graded profiles of the bias magnetic field. We demonstrate spin-wave wavelength conversion upon the wave's reflection from turning points due to the two characteristic minima ("U points") occurring in their dispersion at finite (nonzero) wave vectors. As a result, backward-volume dipole-exchange spin waves confined in "spin-wave wells" either form Möbius modes, making multiple real-space turns for each reciprocal-space round trip, or split into pairs of degenerate modes in the valleys near the two U points. The latter modes may therefore be assigned a pseudospin. We show that the pseudospin can be switched by scattering the spin wave from decreases of the bias magnetic field, while it is immune to scattering from field increases. Pseudospin creation and read-out can be accomplished using chiral spin-wave transducers, as described in Au et al. [Appl. Phys. Lett. 100, 182404 (2012)] and Au et al. [Appl. Phys. Lett. 100, 172408 (2012)], respectively. Taken together, the possibility of pseudospin creation, manipulation, and read-out suggests a path to development of a spin-wave version of valleytronics ("magnon valleytronics"), in which the pseudospin (rather than amplitude or phase) of spin waves would be used to encode data. Our results are not limited to graded bias magnetic field but can be generalized to other magnonic media with spatially varying characteristics, produced using the toolbox of graded index magnonics.

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Topological valley transport of gapped Dirac magnons in bilayer ferromagnetic insulators

Cited by 18 publications

References 60 publications

Dipolar spin-waves and tunable band gap at the Dirac points in the 2D magnet ErBr3

Dipolar spin-waves and tunable band gap at the Dirac points in the 2D magnet ErBr3

Dipolar spin-waves and tunable band gap at the Dirac points in the 2D magnet ErBr3

Spin-wave wells revisited: From wavelength conversion and Möbius modes to magnon valleytronics

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