Bose-glass state in one-dimensional random antiferromagnets

One-dimensional random antiferromagnets (CH3)(2)CHNH3Cu(ClxBr1-x)(3) [abbreviated as IPA-Cu(ClxBr1-x)(3)] show three magnetic phases: Cl rich, intermediate, and Br rich. In this study, to confirm the presence of a gapped or gapless state in addition to a Bose-glass (BG) state of spin triplets at two magnetic phase boundaries, magnetic susceptibility, specific heat, and magnetization were measured. Contrary to our proposed model, the results suggest a gapless state and a BG state at the Br-rich phase boundary, and a spin-gap state at the Cl-rich phase boundary. From the viewpoints of the universality class, the BG state may be interpreted as a result of Anderson localization. Therefore, IPA-Cu(ClxBr1-x)(3) are intriguing compounds for studying the BG state because of good one dimensionality.