Critical magnetic behavior of ferromagnetic CdCr2S4

The critical magnetic behavior of the colossal magnetocapacitive spinel CdCr2S4 is revisited. Magnetization and susceptibility of single-crystalline samples measured in the temperature range 68-120 K were analyzed by the kink-point method, the modified Arrott plots, the Kouvel-Fisher method, ln M versus ln H-eff, and the scaling analysis. We show that the critical exponents beta = 0.365 and gamma = 1.387 of the three-dimensional (3D) Heisenberg model describe the magnetic critical behavior only in the asymptotic region. Outside the asymptotic region, the values of beta are reduced and those of gamma are increased. We provide experimental evidence that the critical behavior of CdCr2S4 follows that expected for an ideal 3D Heisenberg system, however, in an unusual narrow window of temperature and in low magnetic fields only.