Magnetic Excitations Affected By Spin-Lattice Coupling In The S=3/2 Triangular Lattice Antiferromagnet Ag2cro2

Ag2CrO2 is an S = 3/2 triangular lattice antiferromagnet in which long-range magnetic order with a fivefold magnetic unit cell appears below the transition temperature (T-N) of 24 K. The long-range magnetic order is accompanied by a structural transition. Inelastic neutron scattering experiments were performed to investigate the magnetic interactions, anisotropy, and correlations in this material. Above T-N, diffuse scattering originating from the short-ranged magnetic correlations consistent with a 120 degrees structure was observed. The magnetic excitations below T-N were reproduced reasonably well using a linear spin-wave model with further-neighbor interactions and easy-axis anisotropy, which are predicted to be due to a previously proposed spin-lattice coupling [Wang and Vishwanath, Phys. Rev. Lett. 100, 077201 (2008)].