Partially disordered state and spin-lattice coupling in an S=3/2 triangular lattice antiferromagnet Ag2CrO2

TL;DR

This study investigates the complex magnetic and structural behaviors of Ag2CrO2, revealing a unique partially disordered state stabilized by spin-lattice coupling in a frustrated triangular lattice antiferromagnet.

Contribution

It uncovers the emergence of a long-range partially disordered state with 5 sublattices in Ag2CrO2 and highlights the role of spin-lattice coupling in stabilizing this state.

Findings

Partially disordered 5-sublattice state appears at 24 K.

Structural distortion accompanies the magnetic transition.

Spin-lattice coupling stabilizes the anomalous magnetic state.

Abstract

Ag2CrO2 is an S=3/2 frustrated triangular lattice antiferromagnet without orbital degree of freedom. With decreasing temperature, a 4-sublatice spin state develops. However, a long-range partially disordered state with 5 sublattices abruptly appears at TN=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.