Diagonalization of the Antiferromagnetic Magnon-Phonon Interaction

White, Robert M.; Sparks, M.; Ortenburger, I.

doi:10.1103/physrev.139.a450

Cited by 112 publications

(70 citation statements)

References 5 publications

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“…Then, there are two reasons why the magnon-phonon coupling strength can be expected to be strongest around this phonon mode: First, the coupling between quasiparticles is expected to be large when the two modes are close in the momentum-energy space [22,23]. Second, due to the fact that the magnon-phonon coupling is proportional to inverse square-root of energy of phonons [24,25], the contribution of a high energy phonon may be small even if all of phonon modes have the same coupling constant.…”

Section: B Full Hamiltonian With Magnon-phonon Couplingmentioning

confidence: 99%

Magnon-phonon coupling and two-magnon continuum in the two-dimensional triangular antiferromagnetCuCrO2

Park

Leiner

et al. 2016

Phys. Rev. B

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CuCrO2 is a manifestation of a two-dimensional triangular antiferromagnet which exhibits an incommensurate noncollinear magnetic structure similar to a classical 120• ordering. Using the inelastic neutron scattering technique, direct evidence of a magnon-phonon coupling in CuCrO2 is revealed via the mixed magnon-phonon character of the excitation mode at 12.5 meV as well as a minimum at the zone boundary. A simple model Hamiltonian that incorporates an exchange-striction type magnon-phonon coupling reproduces the observed features accurately. Also, continuum excitations originating from the interaction between quasiparticles are observed with strong intensity at the zone boundary. These features of the magnetic excitations are key to an understanding of the emergent excitations in noncollinear antiferromagnetic compounds.

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Section: B Full Hamiltonian With Magnon-phonon Couplingmentioning

confidence: 99%

Magnon-phonon coupling and two-magnon continuum in the two-dimensional triangular antiferromagnetCuCrO2

Park

Leiner

et al. 2016

Phys. Rev. B

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“…We find that both states are locally stable, and exhibit a lowest band with little dispersion, in particular for the 120 o state. We evaluate the spin-wave spectrum of non-collinear spin structures using standard methods [32][33][34] . The Hamiltonian of a Bose gas of magnons reads…”

Section: Linear Spin-wave Theorymentioning

confidence: 99%

Classical dipoles on the kagome lattice

2015

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Motivated by recent developments in magnetic materials, frustrated nanoarrays and cold atomic systems, we investigate the behaviour of dipolar spins on the frustrated two-dimensional kagome lattice. By combining the Luttinger-Tisza approach, numerical energy minimization, spin-wave analysis and parallel tempering Monte-Carlo, we study long-range ordering and finite-temperature phase transitions for a Hamiltonian containing both dipolar and nearest-neighbor interactions. For both weak and moderate dipolar interactions, the system enters a three-sublattice long-range ordered state, with each triangle having vanishing dipole and quadrupole moments; while for dominating dipolar interactions we uncover ferrimagnetic three-sublattice order. These are also the ground states for XY spins. We discuss excitations of, as well as phase transitions into, these states. We find behaviour consistent with Ising criticality for the 120 o state, while the ferrimagnetic state appears to be associated with drifting exponents. The celebrated flat band of zero-energy excitations of the kagome nearest-neighbour Heisenberg model is lifted to finite energies but acquires only minimal dispersion as dipolar interactions are added.

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“…(4). Diagonalizing the quadratic Hamiltonian form using standard methods [20] gives the dispersion relation ω k = A 2 k − B 2 k and the transformation between the original basis and the normal magnon basis…”

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confidence: 99%

Excitations in the quantum paramagnetic phase of the quasi-one-dimensional Ising magnetCoNb2O6in a transverse field: Geometric frustration and quantum renormalization effects

et al. 2014

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The quasi-one-dimensional (1D) Ising ferromagnet CoNb2O6 has recently been driven via applied transverse magnetic fields through a continuous quantum phase transition from spontaneous magnetic order to a quantum paramagnet, and dramatic changes were observed in the spin dynamics, characteristic of weakly perturbed 1D Ising quantum criticality. We report here extensive single-crystal inelastic neutron scattering measurements of the magnetic excitations throughout the three-dimensional (3D) Brillouin zone in the quantum paramagnetic phase just above the critical field to characterize the effects of the finite interchain couplings. In this phase, we observe that excitations have a sharp, resolution-limited line shape at low energies and over most of the dispersion bandwidth, as expected for spin-flip quasiparticles. We map the full bandwidth along the strongly dispersive chain direction and resolve clear modulations of the dispersions in the plane normal to the chains, characteristic of frustrated interchain couplings in an antiferromagnetic isosceles triangular lattice. The dispersions can be well parametrized using a linear spin-wave model that includes interchain couplings and further neighbor exchanges. The observed dispersion bandwidth along the chain direction is smaller than that predicted by a linear spin-wave model using exchange values determined at zero field, and this effect is attributed to quantum renormalization of the dispersion beyond the spin-wave approximation in fields slightly above the critical field, where quantum fluctuations are still significant.

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Diagonalization of the Antiferromagnetic Magnon-Phonon Interaction

Cited by 112 publications

References 5 publications

Magnon-phonon coupling and two-magnon continuum in the two-dimensional triangular antiferromagnetCuCrO2

Magnon-phonon coupling and two-magnon continuum in the two-dimensional triangular antiferromagnetCuCrO2

Classical dipoles on the kagome lattice

Excitations in the quantum paramagnetic phase of the quasi-one-dimensional Ising magnetCoNb2O6in a transverse field: Geometric frustration and quantum renormalization effects

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