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Neutron diffraction study and theoretical analysis of the antiferromagnetic order and the diffuse scattering in the layered kagome system CaBaCo2Fe2 O7

Reim, J. D. ; Rosén, E. ; Zaharko, O. ; Mostovoy, M. ; Robert, J. ; Valldor, M. and Schweika, W. LU (2018) In Physical Review B 97(14).
Abstract

The hexagonal swedenborgite, CaBaCo2Fe2O7, is a chiral frustrated antiferromagnet, in which magnetic ions form alternating kagome and triangular layers. We observe a long-range 3×3 antiferromagnetic order setting in below TN=160 K by neutron diffraction on single crystals of CaBaCo2Fe2O7. Both magnetization and polarized neutron single crystal diffraction measurements show that close to TN spins lie predominantly in the ab plane, while upon cooling the spin structure becomes increasingly canted due to Dzyaloshinskii-Moriya interactions. The ordered structure can be described and refined within the magnetic space group P31m′. Diffuse scattering between the magnetic peaks reveals that the spin order is partial. Monte Carlo simulations... (More)

The hexagonal swedenborgite, CaBaCo2Fe2O7, is a chiral frustrated antiferromagnet, in which magnetic ions form alternating kagome and triangular layers. We observe a long-range 3×3 antiferromagnetic order setting in below TN=160 K by neutron diffraction on single crystals of CaBaCo2Fe2O7. Both magnetization and polarized neutron single crystal diffraction measurements show that close to TN spins lie predominantly in the ab plane, while upon cooling the spin structure becomes increasingly canted due to Dzyaloshinskii-Moriya interactions. The ordered structure can be described and refined within the magnetic space group P31m′. Diffuse scattering between the magnetic peaks reveals that the spin order is partial. Monte Carlo simulations based on a Heisenberg model with two nearest-neighbor exchange interactions show a similar diffuse scattering and coexistence of the 3×3 order with disorder. The coexistence can be explained by the freedom to vary spins without affecting the long-range order, which gives rise to ground-state degeneracy. Polarization analysis of the magnetic peaks indicates the presence of long-period cycloidal spin correlations resulting from the broken inversion symmetry of the lattice, in agreement with our symmetry analysis.

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author
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Review B
volume
97
issue
14
article number
144402
publisher
American Physical Society
external identifiers
  • scopus:85045209919
ISSN
2469-9950
DOI
10.1103/PhysRevB.97.144402
language
English
LU publication?
no
id
b472e09e-fe74-43f9-9367-4436a26eb6ac
date added to LUP
2018-04-26 14:06:23
date last changed
2020-02-12 09:26:16
@article{b472e09e-fe74-43f9-9367-4436a26eb6ac,
  abstract     = {<p>The hexagonal swedenborgite, CaBaCo2Fe2O7, is a chiral frustrated antiferromagnet, in which magnetic ions form alternating kagome and triangular layers. We observe a long-range 3×3 antiferromagnetic order setting in below TN=160 K by neutron diffraction on single crystals of CaBaCo2Fe2O7. Both magnetization and polarized neutron single crystal diffraction measurements show that close to TN spins lie predominantly in the ab plane, while upon cooling the spin structure becomes increasingly canted due to Dzyaloshinskii-Moriya interactions. The ordered structure can be described and refined within the magnetic space group P31m′. Diffuse scattering between the magnetic peaks reveals that the spin order is partial. Monte Carlo simulations based on a Heisenberg model with two nearest-neighbor exchange interactions show a similar diffuse scattering and coexistence of the 3×3 order with disorder. The coexistence can be explained by the freedom to vary spins without affecting the long-range order, which gives rise to ground-state degeneracy. Polarization analysis of the magnetic peaks indicates the presence of long-period cycloidal spin correlations resulting from the broken inversion symmetry of the lattice, in agreement with our symmetry analysis.</p>},
  author       = {Reim, J. D. and Rosén, E. and Zaharko, O. and Mostovoy, M. and Robert, J. and Valldor, M. and Schweika, W.},
  issn         = {2469-9950},
  language     = {eng},
  month        = {04},
  number       = {14},
  publisher    = {American Physical Society},
  series       = {Physical Review B},
  title        = {Neutron diffraction study and theoretical analysis of the antiferromagnetic order and the diffuse scattering in the layered kagome system CaBaCo2Fe2 O7},
  url          = {http://dx.doi.org/10.1103/PhysRevB.97.144402},
  doi          = {10.1103/PhysRevB.97.144402},
  volume       = {97},
  year         = {2018},
}