2008/03/31 by Timothy E. Saunders, J. T. Chalker, John T. Chalker
Physics and Astronomy · #Advanced Condensed Matter Physics #Physics of Superconductivity and Magnetism #Theoretical and Computational Physics #cond-mat.stat-mech #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.77.214438
published as Physical Review B 77, 214438 (2008) · 8 pages, 8 figures
openalex publication_date 2008/06/27 · arxiv created 2008/06/30 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
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 N'eel 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 stabilizes the cubic phase, and we find a phase diagram as a function of temperature and disorder strength similar to that observed in Zn_1\ensuremath-xCdxCr2O4.