Mean-field treatment of nonlinear susceptibilities for a ferromagnet of arbitrary spin
School of Physics, University of Hyderabad - Central University P.O., Hyderabad - 500 046, Andhra Pradesh, India
Accepted: 16 September 2011
The intrinsic linear and nonlinear magnetic susceptibilities, χn, for a ferromagnet of arbitrary spin, calculated using the mean-field approximation, are shown to diverge in the asymptotic critical region (ACR) with the exponent γn=nγ+(n− 1)β and n=1, 2, … . This behaviour of χn in the ACR is consistent with the scaling equation of state. With increasing spin, the divergence in χn(T), as the ferromagnetic-paramagnetic phase transition temperature, TC, is approached from below or above, progressively slows down with the result that the width of the ACR increases. For a given spin, the higher the order of nonlinear susceptibility, the narrower the ACR. These results are in qualitative agreement with the critical behaviour of χn(T) observed in an archetypal ferromagnet.
PACS: 75.40.Cx – Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.) / 75.40.-s – Critical-point effects, specific heats, short-range order / 75.10.Hk – Classical spin models
© EPLA, 2011