139La NMR and 75As NQR study of the As-based filled skutterudite LaOs_4As_(12)

摘要

We report experimental results of nuclear magnetic resonance (NMR) at the La site and nuclear quadrupole resonance (NQR) at the As site in the normal state of the superconducting compound LaOs_4As_(12). Measurements have been performed on powder sample obtained from high quality single crystals. The temperature dependences of the nuclear spinlattice relaxation rates, 1T1, of ~(75)As and ~(139)La nuclei were measured. No scaling between them was found indicating a local character of relaxation processes. The relaxation of ~(75)As nuclei can consistently be understood in terms of antiferromagnetic spin fluctuations, as deduced from the T-dependence of (1T_1T) = C(T-θ)~(1/2).