Chiral Magnetic Effect and Anomalous Hall Effect in Antiferromagnetic Insulators with Spin-Orbit Coupling

Sekine, Akihiko; Nomura, Kentaro

doi:10.1103/physrevlett.116.096401

Cited by 59 publications

(57 citation statements)

References 53 publications

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“…Axion electrodynamics is a useful theory to account for anomaly induced phenomena in chiral media, e.g., the Witten effect [61] the chiral magnetic effect [62][63][64], the anomalous Hall effect [65][66][67][68], etc. Nowadays, Weyl semimetal, topological insulator, and axion crystal provide us with real-world playgrounds of axion electrodynamics, promoting cross-disciplinary studies and experimental searches for anomalous chiral phenomena [69][70][71][72][73][74][75]. In addition to activities in condensed matter physics, one can see recent reviews [76][77][78] for applications of chiral transport phenomena in the high-energy nuclear experiments.…”

Section: Introductionmentioning

confidence: 99%

Anomalous Casimir effect in axion electrodynamics

2019

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We study the Casimir effect in axion electrodynamics. A finite θ-term affects the energy dispersion relation of photon if θ is time and/or space dependent. We focus on a special case with linearly inhomogeneous θ along the z-axis. Then we demonstrate that the Casimir force between two parallel plates perpendicular to the z-axis can be either attractive or repulsive, dependent on the gradient of θ. We call this repulsive component in the Casimir force induced by inhomogeneous θ the anomalous Casimir effect.

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Section: Introductionmentioning

confidence: 99%

Anomalous Casimir effect in axion electrodynamics

2019

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“…Weyl semimetals, which are three-dimensional analogues of graphene, have generated a lot of interest in recent years because of the combination of their peculiar properties [1][2][3][4][5] and experimental accessibility [6][7][8][9][10][11] . Unlike graphene, the gapless nature of the Weyl points in the energy spectrum of a Weyl semimetal are protected by topology through the presence of a non-zero Berry flux in momentum space 4 .…”

Section: Introductionmentioning

confidence: 99%

Role of boundary conditions, topology, and disorder in the chiral magnetic effect in Weyl semimetals

Alavirad

2016

Phys. Rev. B

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Quantum field theory predicts Weyl semimetals to possess a peculiar response of the longitudinal current density to the application of a DC magnetic field. This peculiar response, known as the Chiral Magnetic effect (CME), has been proposed as one of the signatures of the unique chiral anomaly of Weyl nodes. Here we show that such a response can in principle exist in a model without Weyl nodes. On the other hand, such a CME to be at odds with a general result showing the vanishing of the bulk current in an equilibrium system on any real material with a lattice in an external magnetic field. Here we resolve this apparent contradiction by introducing a model where a current flows in response to a magnetic field even without Weyl nodes. We point out that the previous derivation of a vanishing CME in the limit of vanishing real frequency is a consequence of the assumption of periodic boundary conditions of the system. Consistent with recent work, we found the finite frequency CME to be non-vanishing in general when there was a non-vanishing Berry curvature on the Fermi surface. This does not necessitate having a topological Berry flux as in the case of a Weyl node. Finally, we study how the perturbation theory in magnetic field might be more stable in the presence of disorder. We find that in a realistic disordered system, the chiral magnetic response is really a dynamical phenomena and vanishes in the DC limit.

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“…New observations and advances in our understanding have stimulated increased interest in AFM spintronics [2][3][4][5]. AFMs produce no stray fields that can influence other elements.…”

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Spin Superfluidity in Biaxial Antiferromagnetic Insulators

et al. 2017

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Antiferromagnets may exhibit spin superfluidity since the dipole interaction is weak. We seek to establish that this phenomenon occurs in insulators such as NiO, which is a good spin conductor according to previous studies. We investigate nonlocal spin transport in a planar antiferromagnetic insulator with a weak uniaxial anisotropy. The anisotropy hinders spin superfluidity by creating a substantial threshold that the current must overcome. Nevertheless, we show that applying a high magnetic field removes this obstacle near the spin-flop transition of the antiferromagnet. Importantly, the spin superfluidity can then persist across many micrometers, even in dirty samples. DOI: 10.1103/PhysRevLett.118.137201 Introduction.-Achieving long-range spin transport is essential in spintronics. In metals, conduction electrons can carry spin information. The spin-diffusion length is generally less than a few hundred nanometers and often as short as a couple of nanometers. However, in ferromagnets there are additional transport channels via spin excitations, typically in the form of spin waves. In ferromagnetic insulators, the absence of noisy itinerant carriers implies less dissipation such that magnons can traverse distances up to several microns [1]. Magnetic low-damping insulators in which new spin transport mechanisms can exist are of interest and can be promising candidates in low-dissipation spintronics.Antiferromagnets (AFMs) have ordered spin configurations, but there is no net magnetization at equilibrium. New observations and advances in our understanding have stimulated increased interest in AFM spintronics [2][3][4][5]. AFMs produce no stray fields that can influence other elements. There are more known high-temperature AFM insulators and semiconductors than their ferromagnetic counterparts. AFMs exhibit transport properties similar to those of ferromagnets. Some of these features are anisotropic magnetoresistance [6], giant magnetoresistance [7], the large anomalous Hall effect in noncollinear AFMs [8], and the spin Hall effect (SHE) [9]. There are also recent investigations of the spin Seebeck effect in AFMs [10][11][12][13]. Additionally, there are observations of spin transport in AFMs via spin pumping from an adjacent ferromagnet into AFMs [14][15][16][17]. In these experiments, it is possible that (evanescent) magnons carry the spin current [18]. A unique aspect of AFMs is that it is possible to trigger ultrafast THz dynamics of the AFM order parameter via charge [19,20] [26][27][28].In this Letter, we investigate spin transport via spin superfluidity (SSF) in AFM insulators. We focus on NiO as

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Chiral Magnetic Effect and Anomalous Hall Effect in Antiferromagnetic Insulators with Spin-Orbit Coupling

Cited by 59 publications

References 53 publications

Anomalous Casimir effect in axion electrodynamics

Anomalous Casimir effect in axion electrodynamics

Role of boundary conditions, topology, and disorder in the chiral magnetic effect in Weyl semimetals

Spin Superfluidity in Biaxial Antiferromagnetic Insulators

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