Magnetic anomaly in Ni51.5Fe21.5Ga27 single crystalline ferromagnetic shape memory alloy studied by ac impedance measurements

Abstract

[eng] A magnetic anomaly in the austenitic state of Ni51.5Fe21.5Ga27 single crystalline ferromagnetic shape memory alloy has been studied by means of ac impedance measurements. A much stronger effect of the degree of atomic order on the temperature of this anomaly as compared to the temperature of the martensitic and para-ferromagnetic transitions has been found. It has been shown that apart from the previously reported slight variation in the saturation magnetization, the magnetic anomaly results in a nearly one order of magnitude change in the value of initial magnetic permeability. The anomaly is not revealed in the resistive impedance at low frequencies, pointing likely to its purely magnetic origin.