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The spin-lattice relaxation rate T-1(-1) of H-1-NMR has been measured in (CH3)(2)CHNH3Cu(Cl-x,Br1-x)(3) with x = 0.88, which is reportedly a gapped system with a singlet ground state from the previous macroscopic magnetization and specific heat measurements, in order to investigate the bond randomness effect microscopically in the gapped composite Haldane system (CH3)(2)CHNH3CuCl3 It was discovered that the spin-lattice relaxation rate T-1(-1) in the present system includes both fast and slow relaxation parts indicative of the gapless magnetic ground state and the gapped singlet ground state, respectively. We discuss the obtained results with the previous macroscopic magnetization and specific heat measurements together with the microscopic mu SR experiments.

(CH3)(2)CHNH3CuCl3 is described as the spin ladder system, which is composed of a strong ferromagnetic rung and a weak antiferromagnetic leg. Since the ferromagnetic dimer behaves like S=1 spin, this system can be treated as the S=1 quasi-one-dimensional antiferromagnet spin chain (so-called Haldane chain). Cl-NMR study under high-field up to 17.5T has been carried out in order to investigate the field-induced magnetic order in this system. In the lower field region below 10T, the signals from Cl-sites were observed as sharp NMR lines. These paramagnetic lines showed the split above H-N(red) similar or equal to 12T (T=1.85K), demonstrating the existence of the staggered field due to the field-induced magnetic order. Around H-N, the resonance lines disappeared due to the critical slowing down when the applied magnetic field was perpendicular to the ladder, whereas they did not when the field was nearly parallel to the ladder. These results indicate that the spin dynamics around the field-induced magnetic order is anisotropic in this system.

The buckling of CuO2 plane in single crystals of La2-xSrxCuO4 (LSCO) [x = 0.08] and La2-x-yBaySrxCuO4 (LBSCO) [x = 0.06, y = 0.065] was directly observed by high-field Cu-NMR spectra. The split pattern in the NMR spectra of LSCO [x = 0.08] shows that the local structure is Low Temperature Orthorhombic (LTO) like at low temperature, consistent with the results reported by diffraction experiments. In LBCO [x = 0.08], the local structure is Low Temperature Tetragonal (LTT) like, while the averaged structure is reported to be LTO. In LBSCO, the local structure is found to be either LTT-like or Low Temperature Less-Orthorhombic (LTLO) between 35 and 70 K, while the averaged structure is reported to be LTC. With decreasing temperature, the resonance peak disappeared below 35 K, indicating the appearance of Charge Density Wave (CDW) or Spin Density Wave (SDW).

Cu-NMR study has been performed on the disordered spin-gap system Tl1-xKxCuCl3 In the high-field H > H-C=Delta/mu(B), where A is the spin-gap, the hyperfine field becomes extremely inhomogeneous at low temperatures due to the field-induced magnetic order, indicating that the ordered spin state must be different from the pure TlCuCl3. In the low field H < Hc, a saturating behavior in the longitudinal nuclear spin relaxation rate T-1(-1) was observed at low temperatures, indicating existence of the magnetic ground state proposed to be Bose-glass phase by Fisher.

Magnetic torque tau and magnetostriction Delta L/L measurements were carried out in the spin gap system (CH3)(2)CHNH3CuCl3. The magnetic torque shows a cusp-like anomaly at the magnetic field H-a1 with increasing the magnetic field, and the magnetostriction shows a kink at almost the same magnetic field. These results suggest that anomalous change in the magnetic torque is associated with the lattice distortion, and it is expected that the field-induced magnetic phase transition is not simple Bose-Einstein condensation in this system.