Low-Temperature Scaling Of The Susceptibility Of Ni Films

Measurement of low field ac susceptibility of Ni thin films over the temperature range of 5-300 K reveals a surprising power law scaling. The temperature-dependent part of the normalized susceptibility, chi(parallel to)/M-S -chi(rot)/M-S, where chi(parallel to) is the initial susceptibility for in-plane magnetization, chi(rot) is the domain rotation contribution, and M-S is the saturation magnetization, scales with the nonlinear reduced temperature as t(-2) over the entire temperature range, where t = (T-T-C)/(T+T-C) and T-C is the Curie temperature. Thickness and reduced temperature dependences are completely decoupled. This result implies that domain wall motion does not contribute to the low field susceptibility.