Critical spin-glass dynamics in a heterogeneous nanogranular system

The analysis of ac magnetic susceptibility data has shown that mechanically alloyed Fe30Ag40W30, a highly heterogeneous nanogranular system, exhibits critical dynamics in its transition to a low-temperature spin-glass-like phase, as proved by the power-law divergence of the relaxation time at T-g=19.7 K, and by the dynamic scaling behavior of the out-of-phase component of the susceptibility. Both analyses yielded a dynamic critical exponent znu=10.2+/-0.9, confirming the existence of a spin-glass-like phase transition at T-g, which, however, is not accompanied by the usual Mossbauer signature.