Multiple-
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 magnetic orders in Rashba-Dresselhaus metals

Okada, Ken N.; Kato, Yasuyuki; Motome, Yukitoshi

doi:10.1103/physrevb.98.224406

Cited by 22 publications

(13 citation statements)

References 41 publications

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“…In general, the Bloch-and Néel-type multiple-Q spin states are realized under the Rashba-and Dresselhaustype spin-orbit couplings, respectively [57,62]. Note that these spin-orbit couplings are related with each other through π rotation about the [110] or [1 10] axis in spin space [63], being consistent with the relations among the coupling constants above. In the 3D case (d = 3), we choose the same forms of J αα q and D q as Eqs.…”

Section: One-dimensional Casesupporting

confidence: 72%

Spin excitation spectra in helimagnetic states: proper-screw, cycloid, vortex crystal, and hedgehog lattice

Kato,

Hayami,

Motome

2021

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We investigate the spin excitation spectra in chiral and polar magnets by the linear spin-wave theory for an effective spin model with symmetric and antisymmetric long-range interactions. In one dimension, we obtain the analytic form of the dynamical spin structure factor for proper-screw and cycloidal helical spin states with uniform twists, which shows a gapless mode with strong intensity at the helical wave number. When introducing spin anisotropy in the symmetric interactions, we numerically show that the stable spin spirals become elliptically anisotropic with nonuniform twists and the spin excitation is gapped. In higher dimensions, we find that similar anisotropy stabilizes multiple-Q spin states, such as vortex crystals and hedgehog lattices. We show that the anisotropy in these states manifests itself in the dynamical spin structure factor: a strong intensity in the transverse components to the wave number appears only when the helical wave vector and the corresponding easy axis are perpendicular to each other. Our findings could be useful not only to identify the spin structure but also to deduce the stabilization mechanism by inelastic neutron scattering measurements.

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Section: One-dimensional Casesupporting

confidence: 72%

Spin excitation spectra in helimagnetic states: proper-screw, cycloid, vortex crystal, and hedgehog lattice

Kato,

Hayami,

Motome

2021

Preprint

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“…There are mainly two types of effective anisotropic interactions in the lowest order in terms of J: One is the antisymmetric interaction in the form of S q × S −q and the other is the symmetric anisotropic interaction in the form of S x q S x −q and S x q S y −q 78,89,90 . Note that the Hamiltonian H + H ASOC including the other type of spin-orbit coupling was shown to exhibit a variety of multiple-Q magnetic states 91 .…”

Section: F Effect Of Spin-orbit Couplingmentioning

confidence: 99%

Charge density waves in multiple-$Q$ spin states

Hayami,

Motome

2021

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Coupling between spin and charge degrees of freedom in electrons is a source of various electronic and magnetic properties of solids. We theoretically study charge density waves induced by the spin-charge coupling in the presence of magnetic orderings in itinerant magnets. By performing a perturbative calculation in the weakcoupling limit of the Kondo lattice model, we derive a useful formula for the relationship between charge and spin density waves, which can be applied to any magnetic orderings, including noncollinear and noncoplanar ones composed of multiple spin density waves called multiple-Q magnetic orderings. We demonstrate the predictive power for single-Q and double-Q states including skyrmion and meron-antimeron crystals on a square lattice, in comparison with the numerical calculations. Moreover, we show that the charge density waves contain richer information than the spin density waves, and are indeed useful in distinguishing the spin textures with similar spin structure factors. We discuss the relation to bond modulation in terms of the kinetic bond energy and the vector spin chirality. We also perform numerical calculations beyond the perturbative regime and find that the charge density waves can be enhanced when the electron filling is commensurate. Furthermore, we investigate the effect of the spin-orbit coupling, which can lead to additional charge density waves owing to effective anisotropic magnetic interactions in momentum space. Our result will provide a way to identify complex magnetic orderings and their origins from the charge modulations.

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“…Similar attempts have been performed for the situations where the Fermi surface has multiple connections in the extended Brillouin zone [82,83,84] and more generic situations where the Fermi surface has no special property except for the rotational symmetry [85,23]. These considerations have brought about theoretical findings of a plethora of multiple-Q topological spin crystals in hexagonal systems [12,82,156,157,22,158,159,160,161,162,163,164,165], tetragonal systems [166,167,85,168,169,170,171,172], and cubic systems [173,174,175,30,176]. We will review some of these studies in section 3.…”

Section: Frustration In Itinerant Magnetsmentioning

confidence: 86%

Topological spin crystals by itinerant frustration

Hayami,

Motome

2021

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Spin textures with nontrivial topology, such as vortices and skyrmions, have attracted attention as a source of unconventional magnetic, transport, and optical phenomena. Recently, a new generation of topological spin textures has been extensively studied in itinerant magnets; in contrast to the conventional ones induced, e.g., by the Dzyaloshinskii-Moriya interaction in noncentrosymmetric systems, they are characterized by extremely short magnetic periods and stable even in centrosymmetric systems. Here we review such new types of topological spin textures with particular emphasis on their stabilization mechanism. Focusing on the interplay between charge and spin degrees of freedom in itinerant electron systems, we show that itinerant frustration, which is the competition among electron-mediated interactions, plays a central role in stabilizing a variety of topological spin crystals including a skyrmion crystal with unconventional high skyrmion number, meron crystals, and hedgehog crystals. We also show that the essential ingredients in the itinerant frustration are represented by bilinear and biquadratic spin interactions in momentum space. This perspective not only provides a unified understanding of the unconventional topological spin crystals but also stimulates further exploration of exotic topological phenomena in itinerant magnets.

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Multiple- Q magnetic orders in Rashba-Dresselhaus metals

Cited by 22 publications

References 41 publications

Spin excitation spectra in helimagnetic states: proper-screw, cycloid, vortex crystal, and hedgehog lattice

Spin excitation spectra in helimagnetic states: proper-screw, cycloid, vortex crystal, and hedgehog lattice

Charge density waves in multiple-$Q$ spin states

Topological spin crystals by itinerant frustration

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