^63,65Cu-NMR study on Mg-doped quantum spin system TlCu _1-xMg_xCl₃

NMR measurements were carried out on the impurity doped quantum spin system TlCu_1-xMg_xCl₃ with nominal concentration x = 0.03 and 0.01, in which the magnetic phase transition is expected at 3.6 K and 2.2 K, respectively. For the sample x = 0.03, the peaks of NMR spectra split clearly below T = 3.8 K. However, for the sample x = 0.01, no peak splitting was observed down to T = 1.52 K. This result supports the idea of coherent spin fluctuation in the impurity-induced ordered state as suggested by Suzuki et al. [2009 J. Phys. Soc. Jpn. 78 074705.].