Microwave nonreciprocity of magnon excitations in the noncentrosymmetric antiferromagnet 
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Iguchi, Y.; Nii, Yoichi; Kawano, Masataka; Murakawa, H.; Hanasaki, N.

doi:10.1103/physrevb.98.064416

Cited by 17 publications

(16 citation statements)

References 28 publications

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“…2 are identified at 36 µeV and 113 µeV. The latter is consistent with the value reported in previous ESR study [23]. E g of the T 1 mode (E g1 ) is drastically suppressed with the increase of T as shown in Figs.…”

Section: Temperature Dependence Of ∆ Hfsupporting

confidence: 92%

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Nontrivial temperature dependence of magnetic anisotropy in multiferroics Ba$_2$MnGe$_2$O$_7$

Hasegawa¹,

Hayashida²,

Asai³

et al. 2021

Preprint

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We measured the temperature dependences of the static magnetization and the spin excitation in a square-lattice multiferroics Ba 2 MnGe 2 O 7 . An anisotropy gap of the observed low energy mode is scaled by electric polarization rather than a power of sublattice moment. Spin nematic interaction in effective spin Hamiltonian, which is equivalent to interaction of electric polarization, is responsible for the easy-axis anisotropy. The nontrivial behavior of the anisotropy gap can be rationalized as change of the hybridized d-p orbital with temperature, leading to the temperature dependence of the spin nematic interaction.

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Section: Temperature Dependence Of ∆ Hfsupporting

confidence: 92%

“…Drastic T dependence of J N thus results from the change of Λ Z with T ; the modification of the hybridized orbitals of Mn 2+ and O 2− ions with T leads to a small change direction [9]. The dielectric permittivity is ǫ ∼ 14 [23]. We assume that the polarization is localized at each Mn 2+ ion.…”

Section: Temperature Dependence Of ∆ Hfmentioning

confidence: 99%

Nontrivial temperature dependence of magnetic anisotropy in multiferroics Ba$_2$MnGe$_2$O$_7$

Hasegawa¹,

Hayashida²,

Asai³

et al. 2021

Preprint

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“…The 2D Dresselhaus antiferromagnet is actually realized in a noncentrosymmetric spin-5/2 antiferromagnet Ba 2 MnGe 2 O 7 , with space group P42 1 m. It undergoes a Néel transition at T N = 4K into an easy plane type antiferromagnetic phase 36,39 , where the microwave nonreciprocity is indeed observed 40 . A spin-3/2 multiferroic Ba 2 CoGe 2 O 7 41,42 , possibly of space group P42 1 m, is considered to have a similar property.…”

Section: Discussionmentioning

confidence: 98%

Designing Rashba–Dresselhaus effect in magnetic insulators

2019

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One of the major strategies to control magnetism in spintronics is to utilize the coupling between electron spin and its orbital motion. The Rashba and Dresselhaus spin-orbit couplings induce magnetic textures of band electrons called spin momentum locking, which produces a spin torque by the injection of electric current. However, joule heating had been a bottleneck for device applications. Here, we propose a theory to generate further rich spin textures in insulating antiferromagnets with broken spatial inversion symmetry (SIS), which is easily controlled by a small magnetic field. In antiferromagnets, the ordered moments host two species of magnons that serve as internal degrees of freedom in analogy with electron spins. The Dzyaloshinskii-Moriya interaction introduced by the SIS breaking couples the two-magnon-degrees of freedom with the magnon momentum. We present a systematic way to design such texture and to detect it via magnonic spin current for the realization of antiferromagnetic memory.Development of tunable magnetic structure has long been a key issue for detecting and controlling magnetic domains electrically toward application to memory devices 1 . Besides the conventional domain walls that appear in real space, particular focus is given on emergent spin textures in reciprocal space, called "spin momentum locking". The spin textures are classified into Rashba-2-4 and Dresselhaus-types 5 that exhibit vortex-and antivortex geometries along the closed Fermi surfaces. Since the wave number k distinguishes the electronic state of matter, such spin texture allows for the selection of magnetic moment the state/current carries. This has brought about fundamentally important and technologically promising phenomena including spin Hall effect 6-9 , spin-orbit torque 10,11 , and Rashba-Edelstein effect [12][13][14] .In insulating magnets, an excitation is carried by the quasiparticle called magnon, which represents a quantum mechanical spin precession propagating in space. Such propagation is predominantly mediated by the standard magnetic exchange interaction JS i · S j , between spins, S i and S j . In a uniform ferromagnet, a simple exchange interaction, J(< 0), generates non-degenerate quadratic magnon bands. When the spatial inversion symmetry (SIS) is broken, an antisymmetric spin exchange called Dzyaloshinskii-Moriya (DM) interaction 15,16 , D · (S i × S j ), appears, depending on the crystal symmetry. This term bends the propagation of magnons in space in a similar manner to the cyclotron motion of electrons in the presence of magnetic flux 17 . Thus, when D is parallel to the magnetization, magnon bands in a ferromagnet become asymmetric, reflecting the "nonreciprocal" propagation 18-25 . Nevertheless, the phenomena related to magnons in non-centrosymmetric ferro or ferrimagnets lacks abundance compared to the rich counterparts of the conducting Rashba electrons. This is because the ferromagnetic magnons carry spins that are pointing in a unique direction, and cannot afford up and down spin degrees of...

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“…Microwave responses resulting from ferrotoroidic states

\vec{T} = \vec{P} \times \vec{M}

observed experimentally in refs. [], do not clarify the question on a local field (ME field) structure at a dynamic regime.…”

Section: Introductionmentioning

confidence: 99%

Electrodynamics of Magnetoelectric Media and Magnetoelectric Fields

Kamenetskii

2020

Annalen der Physik

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The relationship between magnetoelectricity and electromagnetism is a subject of a strong interest and numerous discussions in microwave and optical wave physics and material sciences. The definition of the energy and momentum of the electromagnetic (EM) field in a magnetoelectric (ME) medium is not a trivial problem. The question of whether electromagnetism and magnetoelectricity can coexist without an extension of Maxwell's theory arises when the effects of EM energy propagation are studied and the group velocity of the waves in an ME medium is considered. The energy balance equation reveals unusual topological structure of fields in ME materials. Together with certain constraints on the constitutive parameters of a medium, definite constraints on the local field structure should be imposed. Analyzing the EM phenomena inside an ME material, the question “what kind of the near fields arising from a sample of such a material can be measured?” should be answered. The visualization of the ME states requires an experimental technique that is based on an effective coupling to the violation of spatial as well as temporal inversion symmetry. To observe the ME energy in a subwavelength region, it is necessary to assume the existence of first‐principle near fields—the ME fields. These are non‐Maxwellian near fields with specific properties of violation of spatial and temporal inversion symmetry. A particular interest to the ME fields arises in studies of metamaterials with “artificial‐atoms” ME elements.

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Microwave nonreciprocity of magnon excitations in the noncentrosymmetric antiferromagnet Ba2MnGe2O7

Cited by 17 publications

References 28 publications

Nontrivial temperature dependence of magnetic anisotropy in multiferroics Ba$_2$MnGe$_2$O$_7$

Nontrivial temperature dependence of magnetic anisotropy in multiferroics Ba$_2$MnGe$_2$O$_7$

Designing Rashba–Dresselhaus effect in magnetic insulators

Electrodynamics of Magnetoelectric Media and Magnetoelectric Fields

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