Structural phase transitions in geometrically frustrated antiferromagnets

Abstract

We study geometrically frustrated antiferromagnets with magnetoelastic coupling. Frustration in these systems may be relieved by a structural transition to a low temperature phase with reduced lattice symmetry. We examine the statistical mechanics of this transition and the effects on it of quenched disorder, using Monte Carlo simulations of the classical Heisenberg model on the pyrochlore lattice with coupling to uniform lattice distortions. The model has a transition between a cubic, paramagnetic high-temperature phase and a tetragonal, Neel ordered low-temperature phase. It does not support the spin-Peierls phase, which is predicted as an additional possibility within Landau theory, and the transition is first-order for reasons unconnected with the symmetry analysis of Landau theory. Quenched disorder stabilises the cubic phase, and we find a phase diagram as a function of temperature and disorder strength similar to that observed in ZnCdCrO.

8 pages, 8 figures

References in corpus (9)

• Exchange Monte Carlo Method and Application to Spin Glass Simulations
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• Low-temperature properties of classical, geometrically frustrated antiferromagnets
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Cited by in corpus (11)

• Predicting the Spin-Lattice Order of Frustrated Systems from First-Principles
• Absent pinch points and emergent clusters: further neighbour interactions in the pyrochlore Heisenberg antiferromagnet
• Spin-glass transition in bond-disordered Heisenberg antiferromagnets coupled with local lattice distortions on a pyrochlore lattice
• Ising Like Order by Disorder In The Pyrochlore Antiferromagnet with Dzyaloshinskii-Moriya Interactions
• Spin-ordering and magnetoelastic coupling in the extended Kagome system YBaCo4O7
• Signatures of magnetostriction and spin-phonon coupling in magnetoelectric hexagonal 15R-BaMnO3
• Spin-Coupled Local Distortions in Multiferroic Hexagonal HoMnO3
• Effect of magnetoelastic coupling on spin-glass behavior in Heisenberg pyrochlore antiferromagnets with bond disorder
• Critical phenomena in a highly constrained classical spin system: Neel ordering from the Coulomb phase
• Nanoscale degeneracy lifting in a geometrically frustrated antiferromagnet
• Extremely slow non-equilibrium monopole dynamics in classical spin ice