Chiral spin-wave edge modes in dipolar magnetic thin films

Shindou, Ryuichi; Ohe, Jun–ichiro; Matsumoto, Ryo; Murakami, Shuichi; Saitoh, Eiji

doi:10.1103/physrevb.87.174402

Cited by 197 publications

(160 citation statements)

References 30 publications

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“…Another possible application is in inversion-invariant systems consisting of arrays of (pseudo)spins with large angular momentum such as in Refs. [17,41,42], where fluctuations above the mean-field treatment are diagonalized by Bogoliubov theory.…”

Section: Discussionmentioning

confidence: 99%

“…We first define the sewing matrix connecting the state at k with the one at −k. If we have a solution of the Bogoliubov equation (17) in momentum space t k , then P B t k diagonalizes H −k . Thus, one can connect the paraunitary matrices at k and −k as…”

Section: Topological Invariantmentioning

confidence: 99%

“…As a result, the condensed part of the atoms has a substantial influence on the topology of the Bogoliubov excitations, which has not been discussed in the previous literature. There are only few articles about the definition of a Chern number for bosonic Bogoliubov bands, though in the context of magnonic systems [16,17].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Topological Bogoliubov excitations in inversion-symmetric systems of interacting bosons

Engelhardt

Brandes

2015

Phys. Rev. A

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On top of the mean-field analysis of a Bose-Einstein condensate, one typically applies the Bogoliubov theory to analyze quantum fluctuations of the excited modes. Therefore, one has to diagonalize the Bogoliubov Hamiltonian in a symplectic manner. In our article we investigate the topology of these Bogoliubov excitations in inversion-invariant systems of interacting bosons. We analyze how the condensate influences the topology of the Bogoliubov excitations. Analogously to the fermionic case, here we establish a symplectic extension of the polarization characterizing the topology of the Bogoliubov excitations and link it to the eigenvalues of the inversion operator at the inversioninvariant momenta. We also demonstrate an instructive but experimentally feasible example that this quantity is also related to edge states in the excitation spectrum.

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Section: Discussionmentioning

confidence: 99%

Section: Topological Invariantmentioning

confidence: 99%

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Topological Bogoliubov excitations in inversion-symmetric systems of interacting bosons

Engelhardt

Brandes

2015

Phys. Rev. A

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“…In contrast to similar procedures on simpler structures [30,31], we account for the internal degrees of freedom resulting from edge modes in the nanoislands. Consequently, we are able to calculate the magnon dispersion as a function of local equilibrium states as well as its field tunability, including edge mode bands.…”

Section: Introductionmentioning

confidence: 99%

Reconfigurable wave band structure of an artificial square ice

et al. 2016

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Artificial square ices are structures composed of magnetic nanoelements arranged on the sites of a twodimensional square lattice, such that there are four interacting magnetic elements at each vertex, leading to geometrical frustration. Using a semianalytical approach, we show that square ices exhibit a rich spin-wave band structure that is tunable both by external magnetic fields and the magnetization configuration of individual elements. Internal degrees of freedom can give rise to equilibrium states with bent magnetization at the element edges leading to characteristic excitations; in the presence of magnetostatic interactions these form separate bands analogous to impurity bands in semiconductors. Full-scale micromagnetic simulations corroborate our semianalytical approach. Our results show that artificial square ices can be viewed as reconfigurable and tunable magnonic crystals that can be used as metamaterials for spin-wave-based applications at the nanoscale.

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“…[47]. Therefore, this analogy leads to the whole phenomenology of Hall effects such as the magnonic 'quantum' Hall effect 31,119,120 , the thermal Hall effect in skyrmion lattices 25 , the Hall effect in frustrated magnets 121 , and the magnonic topological insulators 94,95,[122][123][124][125][126][127][128][129] and their associated topologically protected edge states.…”

mentioning

confidence: 99%

Spin currents and magnon dynamics in insulating magnets

Nakata¹,

Simon²,

Loss³

2017

J. Phys. D: Appl. Phys.

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Nambu-Goldstone theorem provides gapless modes to both relativistic and nonrelativistic systems. The Nambu-Goldstone bosons in insulating magnets are called magnons or spin-waves and play a key role in magnetization transport. We review here our past works on magnetization transport in insulating magnets and also add new insights, with a particular focus on magnon transport. We summarize in detail the magnon counterparts of electron transport, such as the Wiedemann-Franz law, the Onsager reciprocal relation between the Seebeck and Peltier coefficients, the Hall effects, the superconducting state, the Josephson effects, and the persistent quantized current in a ring to list a few. Focusing on the electromagnetism of moving magnons, i.e., magnetic dipoles, we theoretically propose a way to directly measure magnon currents. As a consequence of the Mermin-WagnerHohenberg theorem, spin transport is drastically altered in one-dimensional antiferromagnetic (AF) spin-1/2 chains; where the Néel order is destroyed by quantum fluctuations and a quasiparticle magnon-like picture breaks down. Instead, the low-energy collective excitations of the AF spin chain are described by a Tomonaga-Luttinger liquid (TLL) which provides the spin transport properties in such antiferromagnets some universal features at low enough temperature. Finally, we enumerate open issues and provide a platform to discuss the future directions of magnonics.PACS numbers: Review article for special issue on magnonics from J. Phys. D.

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Chiral spin-wave edge modes in dipolar magnetic thin films

Cited by 197 publications

References 30 publications

Topological Bogoliubov excitations in inversion-symmetric systems of interacting bosons

Topological Bogoliubov excitations in inversion-symmetric systems of interacting bosons

Reconfigurable wave band structure of an artificial square ice

Spin currents and magnon dynamics in insulating magnets

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