Novel critical behavior of magnetization in URhSi; Similarities to the uranium ferromagnetic superconductors UGe and URhGe

Tateiwa, Naoyuki   ; Haga, Yoshinori   ; Yamamoto, Etsuji  

We study the critical behavior of dc magnetization in the uranium ferromagnet URhSi around the ferromagnetic phase transition at 10 K. The critical exponent for the spontaneous magnetization below , for the magnetic susceptibility, and for the magnetic isotherm at have been determined as = 0.300 0.002, = 1.00 0.02, and = 4.32 0.04 by the scaling analysis and the critical isotherm analysis. Magnetization has strong uniaxial magnetic anisotropy in the ferromagnetic state of URhSi. However, the universality class of the critical phenomenon does not belong to the 3D Ising system ( = 0.325, = 1.241, and = 4.82). The obtained exponents in URhSi are similar to those in uranium ferromagnetic superconductors UGe and URhGe. We discuss the static and dynamical magnetic properties of URhSi in comparison with those in UGe, URhGe and UCoGe.