Neutron diffraction study and theoretical analysis of the antiferromagnetic order and diffuse scattering in the layered Kagome system CaBaCo${}_2$Fe${}_2$O${}_7$

Abstract

The hexagonal swedenborgite, CaBaCo${}_2$Fe${}_2$O${}_7$, is a chiral frustrated antiferromagnet, in which magnetic ions form alternating Kagome and triangular layers. We observe a long range $\sqrt{3}\times \sqrt{3}$ antiferromagnetic order setting in below $T_N=160$ K by neutron diffraction on single crystals of CaBaCo${}_2$Fe${}_2$O${}_7$. Both magnetization and polarized neutron single crystal diffraction measurements show that close to $T_N$ 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 $P31m^{\prime }$. 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 $\sqrt{3}\times \sqrt{3}$ 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.

arXiv comment12 pages, 13 figures, 2 tables

References in corpus (12)

• Spontaneous Skyrmion Ground States in Magnetic Metals
• Multiple-q states and skyrmion lattice of the triangular-lattice Heisenberg antiferromagnet under magnetic fields
• Stabilization of Skyrmion textures by uniaxial distortions in noncentrosymmetric cubic helimagnets
• Octupolar ordering of classical kagome antiferromagnets in two and three dimensions
• Magnetic correlations in YBaCo4O7 probed by single-crystal neutron scattering
• Approaching the ground state of the kagome antiferromagnet
• Spin Correlations in the Geometrically Frustrated RBaCo4O7 Antiferromagnets: Mean-Field Approach and Monte-Carlo Simulations
• XYZ-polarisation analysis of diffuse magnetic neutron scattering from single crystals
• Spin dynamics, short range order and spin freezing in Y0.5Ca0.5BaCo4O7
• Spin correlations in the extended kagome system YBaCo3FeO7
• Spin-liquid phase and order-by-disorder of classical Heisenberg spins on the swedenborgite lattice
• A possible chiral spin-liquid phase in non-centrosymmetric $R$BaCo${}_4$O${}_7$

Cited by in corpus (4)

• The 2020 Skyrmionics Roadmap
• Microscopic mechanism for intrinsic nonlinear anomalous Hall conductivity in noncollinear antiferromagnetic metals
• Spin-lattice and magnetoelectric couplings enhanced by orbital degrees of freedom in polar magnets
• Magnetic particles and strings in iron langasite