Spin correlations in the geometrically frustrated RBaCo{sub 4}O{sub 7} antiferromagnets : mean-field approach and Monte-Carlo simulations.

Journal Article · Wed Sep 01 04:00:00 EDT 2010 · Phys. Rev. B

DOI:https://doi.org/10.1103/PhysRevB.82.094401· OSTI ID:993391

Khalyavin, D D; Manuel, P; Mitchell, J F; Chapon, L C

Spin correlations in the geometrically frustrated RBaCo{sub 4}O{sub 7} compounds, usually described as an alternating stacking of Kagome and triangular layers on a hexagonal lattice, have been studied by mean-field approach and by Monte Carlo simulations. The behavior of the system was modeled with an isotropic Heisenberg Hamiltonian as a function of the relevant parameter J{sub out}/J{sub in}, representing the ratio between exchange integrals inside the Kagome layers, J{sub in}, and between Kagome and triangular layers, J{sub out}. This ratio can be varied in real systems by appropriate chemical substitutions. At the mean-field level, long-range magnetic order with the wave vector at the K point of symmetry (k=a*/3+b*/3) has been found for J{sub out}/J{sub in} > 0.7. Below this value, the dominant Fourier modes are completely degenerate in the entire Brillouin zone. The Monte Carlo simulations revealed that the long-range ordered configuration found in the mean-field calculations becomes the ground state of the system for J{sub out}/J{sub in} > 1.5. Below this critical ratio, quasi-one-dimensional magnetic ordering along the c axis, involving spins of the triangular sublattice was observed. The correlations in the (ab) plane were found to have a short-range 120{sup o} character with correlation length dependent on J{sub out}/J{sup in}.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 993391
• Report Number(s): ANL/MSD/JA-67530
• Journal Information: Phys. Rev. B, Journal Name: Phys. Rev. B Journal Issue: Sep. 1, 2010 Vol. 82; ISSN 1098-0121
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BRILLOUIN ZONES
CONFIGURATION
GROUND STATES
HAMILTONIANS
HEXAGONAL LATTICES
SPIN
SYMMETRY
VECTORS