Spin-glass behavior in CeCu₂-type uranium compound U ₂AuGa₃

We present the results of ac and dc susceptibility, magnetization, magnetic relaxation, specific heat, and electrical resistivity measurements on U2 AuGa3, an orthorhombic CeCu2 -type nonmagnetic atom disorder system. These data clearly indicate that U2 AuGa3 undergoes a spin glass phase transition at a static freezing temperature Ts =23.6 K, in spite of the lack of triangular magnetic structure. It is observed that the variation of the characteristic temperature Tir (the bifurcation point between field-cooled and zero-field-cooled susceptibilities) with applied field H for U2 AuGa3 is not consistent with the "AT line," but follows a Tir ∝- H25 law. The observed spin glass behavior and the formation of frustrated magnetic interactions in U2 AuGa3 are discussed in a magnetic cluster model.