Spin-glass transition in bond-disordered Heisenberg antiferromagnets coupled with local lattice distortions on a pyrochlore lattice

Abstract

Motivated by puzzling characteristics of spin-glass transitions widely observed in pyrochlore-based frustrated materials, we investigate effects of coupling to local lattice distortions in a bond-disordered antiferromagnet on the pyrochlore lattice by extensive Monte Carlo simulations. We show that the spin-glass transition temperature $\TSG$ is largely enhanced by the spin-lattice coupling, and furthermore, becomes almost independent of $\Delta$ in a wide range of the disorder strength $\Delta$. The critical property of the spin glass transition is indistinguishable from that of the canonical Heisenberg spin glass in the entire range of $\Delta$. These peculiar behaviors are ascribed to a modification of the degenerate manifold from continuous to semidiscrete one by the spin-lattice coupling.