2009/03/13 by A. Oosawa, T. Suzuki, Oosawa, A. +7
Physics and Astronomy · #FOS: Physical sciences #Statistical Mechanics (cond-mat.stat-mech) #cond-mat.stat-mech
paper · pdf · doi:10.48550/arxiv.0903.2318
submitted to JPSJ (accepted and will appear in the issue of No. 5)
arxiv created 2009/03/20 · arxiv updated 2009/12/01
The spin-lattice relaxation rate T1-1 of 1H-NMR has been measured in (CH3)2CHNH3Cu(ClxBr1-x)3 with x=0 and 0.35, in order to investigate the microscopic magnetism of systems. Previous macroscopic magnetization and specific heat measurements suggested that these two exist in a singlet-dimer phase. The temperature dependence of T1-1 in an x=0 system decreased exponentially toward zero, indicating microscopic evidence of the gapped singlet ground state, which is consistent with the macroscopic experiments. At the same time, in the x=0.35 system, T1-1 showed a sharp peak structure at around 7.5 K though no splitting of 1H-NMR spectra indicative of the magnetic ordering was observed. We discuss the observed sharp peak structure in the x=0.35 system with the soft mode toward the exotic magnetic ground state suggested by the recent μSR experiments.