Magneto-Impedance measurements in thin films of the Spin-Glass Cu100-xMnxAu13.5 (x = 6.75 and 13.5) alloys

Abstract

Magneto-impedance measurements (MI) were carried out on thin-films of Cu100-xMnxAu13.5 (x = 6.75 and 13.5). The sample with × = 6.75 (13.5) undergoes a phase transition to a spin-glass state below a glass temperature of about TG = 31 K (55 K). The MI measurements were carried out for temperatures (T) from 300 K down to 5 K in applied magnetic fields in the range of ± 3.5 kOe and for an ac electric current with frequency of 9.0 MHz. Short-range interaction and spin-fluctuations yielded non-vanishing values for the MI data for all values of T. The transverse magnetic permeability (μT) was obtained for both sample compositions demonstrating that MI is a suitable technique to study canonical spin-glasses in the MHz regime. Moreover, it was observed that the spin-fluctuations in very short time scale (∼10−7 s) are important down to the lowest temperature investigated of 5 K. The transverse magnetic susceptibility, μT, showed a minimum near the freezing temperature.