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

Abstract

Low-temperature ac and de magnetic susceptibility and specific-heat measurements have been carried out on YNd di1ute 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 Iong-range antiferromagnetic spin-density-wave (SDW) order be1ow the criticai temperature, but some residual frustration is 1ikely to produce a reentrant behavior at Iow 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.