title: Spin-Lattice-Coupled Order in Heisenberg Antiferromagnets on the Pyrochlore Lattice.
abstract: Effects of local lattice distortions on the spin ordering are investigated for the antiferromagnetic classical Heisenberg model on the pyrochlore lattice. It is found by Monte Carlo simulations that the spin-lattice coupling (SLC) originating from site phonons induces a first-order transition into two different types of collinear magnetic ordered states. The state realized at the stronger SLC is cubic symmetric characterized by the magnetic (1/2,1/2,1/2) Bragg peaks, while that at the weaker SLC is tetragonal symmetric characterized by the (1,1,0) ones, each accompanied by the commensurate local lattice distortions. Experimental implications to chromium spinels are discussed.
authors.affiliation: Department of Earth and Space Science, Graduate School of Science, Osaka University, Osaka 560-0043, Japan.
authors.forename: Kazushi
authors.initials: K
authors.lastname: Aoyama
authors.affiliation: Department of Earth and Space Science, Graduate School of Science, Osaka University, Osaka 560-0043, Japan.
authors.forename: Hikaru
authors.initials: H
authors.lastname: Kawamura