Dynamic Properties of a Reentrant Spin Glass Pd_1-x-yFe_xMn_y

Abstract

We have previously studied the reentrant behavior of Pd_1-x-yFe_xMn_y alloy and obtained a phase diagram for the alloy[1]. A Gabay-Toulouse transition [T_GT(ω)] was found in Pd_1-x-yFe_xMn_y by Mössbauer spectroscopy[2] and magnetization measurement[3]. Recently, the frequency dependence of T_GT(ω), the peak temperature of the imaginary part of the ac-susceptibility of Pd_0.920Fe_0.015Mn_0.065, has been well analyzed using a dynamic scaling relation ω/ω ₀ = [{T_GT(ω)-T_GT(0)}/T_GT(ω)]^{Z V}[4] proposed by SOULETIE and THOLENCE[5] and SOULETIE[6]. From the analysis, the finite temperature Gabay-Toulouse transition was suggested. We study here the time decay of a thermoremanent magnetization (TRM) M_TRM(t) for Pd_1-x-yFe_xMn_y. In the ferromagnetic phase of two samples,Pd_0.920Fe_0.015Mn_0.065 (T_c=26.5 K, T_GT=3.6 K) and Pd_0.881Fe_0.027Mn_0.092 (T_c=34 K, T_GT=13.2 K), short-time relaxation (t<~30 sec) curves at the cooling field H=500 Oe are represented by a single exponential form. Its characteristic time τ is about 4 sec for Pd_0.920Fe_0.015Mn_0.065. On the other hand, the long-time tail of the log-log plot of the TRM is nearly represented by a straight line for these samples. This fact shows that the time behavior of the TRM in this region follows a power law.