Partially disordered state and spin-lattice coupling in an $S=\frac{3}{2}$ triangular lattice antiferromagnet Ag${}_{2}$CrO${}_{2}$

Partially disordered state and spin-lattice coupling in an $S = \frac{3}{2}$ triangular lattice antiferromagnet Ag $_{2}$ CrO $_{2}$

M. Matsuda, C. de la Cruz, H. Yoshida, M. Isobe, and R. S. Fishman

Phys. Rev. B 85, 144407 – Published 11 April 2012

Abstract

Ag $_{2}$ CrO $_{2}$ is an $S = 3 / 2$ frustrated triangular lattice antiferromagnet without an orbital degree of freedom. With decreasing temperature, a four-sublattice spin state develops. However, a long-range partially disordered state with five sublattices abruptly appears at $T_{N} = 24$ K, accompanied by a structural distortion, and persists at least down to 2 K. The spin-lattice coupling stabilizes the anomalous state, which is expected to appear only in limited ranges of further-neighbor interactions and temperature. It was found that the spin-lattice coupling is a common feature in triangular lattice antiferromagnets with multiple-sublattice spin states, since the triangular lattice is elastic.