Torque equilibrium spin wave theory study of anisotropy and Dzyaloshinskii-Moriya interaction effects on the indirect K -edge RIXS spectrum of a triangular lattice antiferromagnet

Shangjian Jin, Cheng Luo, Trinanjan Datta, Dao Xin Yao

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Abstract

We apply the recently formulated torque equilibrium spin wave theory (TESWT) to compute the 1/S-order interacting K-edge bimagnon resonant inelastic x-ray scattering (RIXS) spectra of an anisotropic triangular lattice antiferromagnet with Dzyaloshinskii-Moriya (DM) interaction. We extend the interacting torque equilibrium formalism, incorporating the effects of DM interaction, to appropriately account for the zero-point quantum fluctuation that manifests as the emergence of spin Casimir effect in a noncollinear spin spiral state. Using inelastic neutron scattering data from Cs2CuCl4 we fit the 1/S-corrected TESWT dispersion to extract exchange and DM interaction parameters. We use these new fit coefficients alongside other relevant model parameters to investigate, compare, and contrast the effects of spatial anisotropy and DM interaction on the RIXS spectra at various points across the Brillouin zone. We highlight the key features of the bi- and trimagnon RIXS spectrum at the two inequivalent rotonlike points, M(0,2π/3) and M′(π,π/3), whose behavior is quite different from an isotropic triangular lattice system. While the roton RIXS spectrum at the M point undergoes a spectral downshift with increasing anisotropy, the peak at the M′ location loses its spectral strength without any shift. With the inclusion of DM interaction the spiral phase is more stable and the peak at both M and M′ point exhibits a spectral upshift. Our calculation offers a practical example of how to calculate interacting RIXS spectra in a noncollinear quantum magnet using TESWT. Our findings provide an opportunity to experimentally test the predictions of interacting TESWT formalism using RIXS, a spectroscopic method currently in vogue.

Original languageEnglish (US)
Article number054410
JournalPhysical Review B
Volume100
Issue number5
DOIs
StatePublished - Aug 8 2019

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Spin waves
x ray scattering
magnons
torque
inelastic scattering
Anisotropy
Torque
Scattering
X rays
anisotropy
interactions
Inelastic neutron scattering
formalism
rotons
Magnets
Brillouin zones
neutron scattering
magnets
inclusions
shift

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

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title = "Torque equilibrium spin wave theory study of anisotropy and Dzyaloshinskii-Moriya interaction effects on the indirect K -edge RIXS spectrum of a triangular lattice antiferromagnet",
abstract = "We apply the recently formulated torque equilibrium spin wave theory (TESWT) to compute the 1/S-order interacting K-edge bimagnon resonant inelastic x-ray scattering (RIXS) spectra of an anisotropic triangular lattice antiferromagnet with Dzyaloshinskii-Moriya (DM) interaction. We extend the interacting torque equilibrium formalism, incorporating the effects of DM interaction, to appropriately account for the zero-point quantum fluctuation that manifests as the emergence of spin Casimir effect in a noncollinear spin spiral state. Using inelastic neutron scattering data from Cs2CuCl4 we fit the 1/S-corrected TESWT dispersion to extract exchange and DM interaction parameters. We use these new fit coefficients alongside other relevant model parameters to investigate, compare, and contrast the effects of spatial anisotropy and DM interaction on the RIXS spectra at various points across the Brillouin zone. We highlight the key features of the bi- and trimagnon RIXS spectrum at the two inequivalent rotonlike points, M(0,2π/3) and M′(π,π/3), whose behavior is quite different from an isotropic triangular lattice system. While the roton RIXS spectrum at the M point undergoes a spectral downshift with increasing anisotropy, the peak at the M′ location loses its spectral strength without any shift. With the inclusion of DM interaction the spiral phase is more stable and the peak at both M and M′ point exhibits a spectral upshift. Our calculation offers a practical example of how to calculate interacting RIXS spectra in a noncollinear quantum magnet using TESWT. Our findings provide an opportunity to experimentally test the predictions of interacting TESWT formalism using RIXS, a spectroscopic method currently in vogue.",
author = "Shangjian Jin and Cheng Luo and Trinanjan Datta and Yao, {Dao Xin}",
year = "2019",
month = "8",
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language = "English (US)",
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T1 - Torque equilibrium spin wave theory study of anisotropy and Dzyaloshinskii-Moriya interaction effects on the indirect K -edge RIXS spectrum of a triangular lattice antiferromagnet

AU - Jin, Shangjian

AU - Luo, Cheng

AU - Datta, Trinanjan

AU - Yao, Dao Xin

PY - 2019/8/8

Y1 - 2019/8/8

N2 - We apply the recently formulated torque equilibrium spin wave theory (TESWT) to compute the 1/S-order interacting K-edge bimagnon resonant inelastic x-ray scattering (RIXS) spectra of an anisotropic triangular lattice antiferromagnet with Dzyaloshinskii-Moriya (DM) interaction. We extend the interacting torque equilibrium formalism, incorporating the effects of DM interaction, to appropriately account for the zero-point quantum fluctuation that manifests as the emergence of spin Casimir effect in a noncollinear spin spiral state. Using inelastic neutron scattering data from Cs2CuCl4 we fit the 1/S-corrected TESWT dispersion to extract exchange and DM interaction parameters. We use these new fit coefficients alongside other relevant model parameters to investigate, compare, and contrast the effects of spatial anisotropy and DM interaction on the RIXS spectra at various points across the Brillouin zone. We highlight the key features of the bi- and trimagnon RIXS spectrum at the two inequivalent rotonlike points, M(0,2π/3) and M′(π,π/3), whose behavior is quite different from an isotropic triangular lattice system. While the roton RIXS spectrum at the M point undergoes a spectral downshift with increasing anisotropy, the peak at the M′ location loses its spectral strength without any shift. With the inclusion of DM interaction the spiral phase is more stable and the peak at both M and M′ point exhibits a spectral upshift. Our calculation offers a practical example of how to calculate interacting RIXS spectra in a noncollinear quantum magnet using TESWT. Our findings provide an opportunity to experimentally test the predictions of interacting TESWT formalism using RIXS, a spectroscopic method currently in vogue.

AB - We apply the recently formulated torque equilibrium spin wave theory (TESWT) to compute the 1/S-order interacting K-edge bimagnon resonant inelastic x-ray scattering (RIXS) spectra of an anisotropic triangular lattice antiferromagnet with Dzyaloshinskii-Moriya (DM) interaction. We extend the interacting torque equilibrium formalism, incorporating the effects of DM interaction, to appropriately account for the zero-point quantum fluctuation that manifests as the emergence of spin Casimir effect in a noncollinear spin spiral state. Using inelastic neutron scattering data from Cs2CuCl4 we fit the 1/S-corrected TESWT dispersion to extract exchange and DM interaction parameters. We use these new fit coefficients alongside other relevant model parameters to investigate, compare, and contrast the effects of spatial anisotropy and DM interaction on the RIXS spectra at various points across the Brillouin zone. We highlight the key features of the bi- and trimagnon RIXS spectrum at the two inequivalent rotonlike points, M(0,2π/3) and M′(π,π/3), whose behavior is quite different from an isotropic triangular lattice system. While the roton RIXS spectrum at the M point undergoes a spectral downshift with increasing anisotropy, the peak at the M′ location loses its spectral strength without any shift. With the inclusion of DM interaction the spiral phase is more stable and the peak at both M and M′ point exhibits a spectral upshift. Our calculation offers a practical example of how to calculate interacting RIXS spectra in a noncollinear quantum magnet using TESWT. Our findings provide an opportunity to experimentally test the predictions of interacting TESWT formalism using RIXS, a spectroscopic method currently in vogue.

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