Weyl magnons in pyrochlore antiferromagnets with an all-in-all-out order

Jian, Shao-Kai; Nie, Wenxing

doi:10.1103/physrevb.97.115162

Cited by 58 publications

(47 citation statements)

References 61 publications

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“…They are three-dimensional magnets with conelike band touching points. Explicit Hamiltonians have been constructed in two contexts: breathing pyrochlore antiferromagnets [25,30] as well as stacked Kagome antiferromagnets [56]. In both cases, the Hamiltonian is very close to the bosonic Dirac form.…”

Section: Discussionmentioning

confidence: 99%

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Dirac Hamiltonians for bosonic spectra

Kumar

Herbut

Ganesh

2020

Phys. Rev. Research

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Dirac materials are of great interest as condensed matter realizations of the Dirac and Weyl equations. In particular, they serve as a starting point for the study of topological phases. This physics has been extensively studied in electronic systems such as graphene, Weyl, and Dirac semimetals. In contrast, recent studies have highlighted several examples of Dirac-like cones in collective excitation spectra, viz. in phonon, magnon, and triplon bands. These cannot be directly related to the Dirac or Weyl equations as they are bosonic in nature with pseudounitary band bases. We address this issue by constructing a generic deformation scheme that maps any fermionic Hamiltonian and its spectrum to that of a bosonic problem. In particular, we show that any Dirac-like equation can be deformed into a suitable bosonic form. The resulting bosonic spectra bear a two-to-one relation to that of the parent Dirac system. Their dispersions inherit several interesting properties including conical band touching points and a gap-opening role for 'mass' terms. The relationship also extends to the band eigenvectors with the bosonic states carrying the same Berry connections as the parent fermionic states. The bosonic bands thus inherit topological character as well. If the parent fermionic system has nontrivial topology that leads to midgap surface states, the bosonic analog also hosts surface states that lie within the corresponding band gap. The proposed bosonic Dirac structure appears in several known models. In materials, it is realized in Ba 2 CuSi 2 O 6 Cl 2 and possibly in CoTiO 3 as well as in paramagnetic honeycomb ruthenates. Our results allow for a rigorous understanding of Dirac phononic and magnonic systems and enable concrete predictions, e.g., of surface states in magnonic topological insulators and Weyl semimetals.

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Section: Discussionmentioning

confidence: 99%

“…These include plasmons [9], phonons [10][11][12][13], photons [14][15][16][17][18], magnons [3,[19][20][21][22], and triplons [6,23,24]. There has also been an explosion of interest in 'Weyl points' in magnonic band structures [25][26][27][28][29][30]. Do these constitute Dirac systems?…”

Section: Introductionmentioning

confidence: 99%

Dirac Hamiltonians for bosonic spectra

Kumar

Herbut

Ganesh

2020

Phys. Rev. Research

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“…As a representative subject of quantum magnetism, pyrochlore antiferromagnets have attracted a significant attention in recent years [1]. Many interesting phenomena including classical spin ice [2,3], quantum spin ice [4][5][6], pyrochlore ice U(1) spin liquid [5,[7][8][9][10], quantum order by disorder [11,12], spin nematics [13,14], symmetry enriched topological orders [10,15,16], topological magnetic excitations [17][18][19] have been proposed and/or discovered for various compounds in the pyrochlore antiferromagnet families. While most efforts of this field have been devoted to the antiferromagnets, the pyrochlore ferromagnet Lu 2 V 2 O 7 may stand out in the field of pyrochlore magnets by providing some rather unique and robust phenomena [20][21][22][23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Asymmetric ferromagnetic criticality in pyrochlore ferromagnet Lu2V2O7

Jiao

et al. 2019

Science Bulletin

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We study the ferromagnetic criticality of the pyrochlore magnet Lu 2 V 2 O 7 at the ferromagnetic transition T C % 70 K from the isotherms of magnetization MðHÞ via an iteration process and the Kouvel-Fisher method. The critical exponents associated with the transition are determined: b = 0.32(1), c = 1.41(1), and d ¼ 5:38. The validity of these critical exponents is further verified by scaling all the MðHÞ data in the vicinity of T C onto two universal curves in the plot of M=jej b versus H=jej bþc , where e ¼ T=T C À 1. The obtained b and c values show asymmetric behaviors on the T < T C and the T > T C sides, and are consistent with the predicted values of 3D Ising and cubic universality classes, respectively. This makes Lu 2 V 2 O 7 a rare example in which the critical behaviors associated with a ferromagnetic transition belong to different universality classes. We describe the observed criticality from the Ginzburg-Landau theory with the quartic cubic anisotropy that microscopically originates from the anti-symmetric Dzyaloshinskii-Moriya interaction as revealed by recent magnon thermal Hall effect and theoretical investigations.

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“…Breathing pyrochlore lattice materials have recently emerged as an interesting route to study various aspects of frustrated magnetism [1][2][3][4][5][6][7][8][9][10][11]. Examples include the potentially enhanced stability of quantum spin ice state [10], as well as the appearance of a "Weyl magnon", a bosonic analog of a Weyl fermion [12][13][14], which hosts the associated magnon arc surface states [12].…”

Section: Introductionmentioning

confidence: 99%

Behavior of the breathing pyrochlore lattice Ba₃Yb₂Zn₅O₁₁ in applied magnetic field

Rau

May

et al. 2018

J. Phys.: Condens. Matter

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The breathing pyrochlore lattice material Ba 3 Yb 2 Zn 5 O 11 exists in the nearly decoupled limit, in contrast to most other well-studied breathing pyrochlore compounds. As a result, it constitutes a useful platform to benchmark theoretical calculations of exchange interactions in insulating Yb 3+ magnets. Here we study Ba 3 Yb 2 Zn 5 O 11 at low temperatures in applied magnetic fields as a further probe of the physics of this model system. Experimentally, we consider the behavior of polycrystalline samples of Ba 3 Yb 2 Zn 5 O 11 with a combination of inelastic neutron scattering and heat capacity measurements down to 75 mK and up to fields of 10 T. Consistent with previous work, inelastic neutron scattering finds a level crossing near 3 T, but no significant dispersion of the spin excitations is detected up to the highest applied fields. Refinement of the theoretical model previously determined at zero field can reproduce much of the inelastic neutron scattering spectra and specific heat data. A notable exception is a low temperature peak in the specific heat at ∼ 0.1 K. This may indicate the scale of interactions between tetrahedra or may reflect undetected disorder in Ba 3 Yb 2 Zn 5 O 11 . a

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Weyl magnons in pyrochlore antiferromagnets with an all-in-all-out order

Cited by 58 publications

References 61 publications

Dirac Hamiltonians for bosonic spectra

Dirac Hamiltonians for bosonic spectra

Asymmetric ferromagnetic criticality in pyrochlore ferromagnet Lu2V2O7

Behavior of the breathing pyrochlore lattice Ba₃Yb₂Zn₅O₁₁ in applied magnetic field

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Weyl magnons in pyrochlore antiferromagnets with an all-in-all-out order

Cited by 58 publications

References 61 publications

Dirac Hamiltonians for bosonic spectra

Dirac Hamiltonians for bosonic spectra

Asymmetric ferromagnetic criticality in pyrochlore ferromagnet Lu2V2O7

Behavior of the breathing pyrochlore lattice Ba3Yb2Zn5O11 in applied magnetic field

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Product

Resources

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Behavior of the breathing pyrochlore lattice Ba₃Yb₂Zn₅O₁₁ in applied magnetic field