Evidence of spin-density-wave to spin-glass transformation in YNd alloys

Abstract

Low-temperature ac and dc magnetic susceptibility and specific-heat measurements have been carried out on YNd dilute alloys, where the Nd concentrations are 1.9, 2.5, 4.5, 6.8, and 9.0 at. %. The most concentrated alloys (4.5, 6.8, and 9.0 at. %) present long-range antiferromagnetic spin-density-wave (SDW) order below the critical temperature, but some residual frustration is likely to produce a reentrant behavior at low temperatures, where the magnetic data show strong irreversibility effects and the specific heat indicates the occurrence of an anisotropy induced gap near zero frequency in the density of states of the magnetic excitations. For the less concentrated alloys (1.9 and 2.5 at. %), the interacting magnetic state shows typical features of spin-glass behavior. The evolution to this state is ascribed as being due to impurity disorder and frustration which induces a breaking up of the SDW coherence into small domains.