Critical behavior of magnetization in URhAl; Quasi-two-dimensional Ising system with long-range interactions

URhAlの強磁性転移における二次元的臨界現象

立岩 尚之   ; Pospil, J.*; 芳賀 芳範   ; 山本 悦嗣  

Tateiwa, Naoyuki; Pospil, J.*; Haga, Yoshinori; Yamamoto, Etsuji

強磁性体URhAlの磁気臨界現象を研究した。自発磁化の臨界指数、磁化率の指数、強磁性転移温度における磁化の臨界指数を求めた。それぞれ=0.2870.005, =1.470.02, =6.080.04と決定された。これらの臨界指数はWidomのスケーリング則()を満たしている。得られた結果は、二次元イジングモデルについての繰り込み群を用いた理論モデルで説明される。

The critical behavior of dc magnetization in the uranium ferromagnet URhAl with the hexagonal ZrNiAl-type crystal structure has been studied around the ferromagnetic transition temperature . The critical exponent for the temperature dependence of the spontaneous magnetization below , for the magnetic susceptibility, and for the magnetic isotherm at have been obtained. We have determined the critical exponents as = 0.287 0.005, = 1.47 0.02, and = 6.08 0.04 by the scaling analysis and the critical isotherm analysis. These critical exponents satisfy the Widom scaling law . The determined exponents can be explained with the results of the renormalization group approach for a two-dimensional Ising system coupled with long-range interactions.