139La NMR and 75As NQR study of the As-based filled skutterudite LaOs4As12

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 LaOs4As12. Measurements have been performed on powder sample obtained from high quality single crystals. The temperature dependences of the nuclear spin–lattice relaxation rates, 1 / T 1 , of 75As and 139La nuclei were measured. No scaling between them was found indicating a local character of relaxation processes. The relaxation of 75As nuclei can consistently be understood in terms of antiferromagnetic spin fluctuations, as deduced from the T -dependence of ( 1 / T 1 T ) = C / ( T − θ ) 1 / 2 .