Cu-NMR study on the disordered quantum spin magnet with the Bose-glass   ground state
  Cu-NMR study has been performed on the disordered spin-gap system Tl1-xKxCuCl3 In the high-field H > HC=\Delta/\mu_B, where \Delta 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 1/T1 was observed at low temperatures, indicating existence of the magnetic ground state proposed to be Bose-glass phase by Fisher. 
T. Fujiwara, H. Inoue, A. Oosawa, R. Tsunoda, T. Goto, T. Suzuki, Y.   Shindo, H. Tanaka, T. Sasaki, N. Kobayashi, S. Awaji,...