Antiferromagnetic resonance in the quasi-one-dimensional magnet IPACu(Cl x Br1−x )3 (x=0.83)

Abstract

We have performed multi-frequency electron spin resonance (ESR) and magnetization measurements on single crystals of the quasi one-dimensional magnet IPACu(Cl x Br1−x )3 (x=0.83) in magnetic fields H along the b-axis at temperatures below an antiferromagnetic long-range ordering temperature (T N ≅ 13 K). We observed some ESR branches for typical antiferromagnetic modes with biaxial anisotropy at 1.5 K (≪ T N). We have analyzed the magnetization curve and the ESR excitation modes for H∥b by using a two sub-lattice model and obtained good agreement between experiment and calculation. In addition, we show that the origin of a field-induced magnetization jump is a spin-flop transition. These results show that the phase at temperatures below T N in this Cl-Br mixed compound can be described as a simple two sub-lattice antiferromagnet.