ac susceptibility and electrical resistivity measurements on the spin-glass phase ofPdMn

Abstract

Measurements of the ac susceptibility and electrical resistivity of 11 $\mathrm{Pd}\mathrm{Mn}$ alloys containing between 5.5 and 10.45 at.% Mn are presented as a function of temperature from 1.4 to 20 K. The zero-field ac susceptibility exhibits a peak whose position and height is modified by the application of static biasing fields. These data, however, do not obey either the geometrical Ruderman-Kittel-Kasuya-Yosida (RKKY) scaling relationships or recent predictions based on a short-range model for spin-glasses. The incremental resistivity follows a linear temperature dependence at lower concentration and a $T^{\frac{3}{2}}$ limiting form at higher concentration. The range of validity of these dependences imply that they cannot originate from conduction-electron scattering simply from low-lying excitations. We conclude that existing theories do not adequately account for the processes occurring in $\mathrm{Pd}\mathrm{Mn}$ alloys where the upper spin-glass state results from competing interactions between a long-range ferromagnetic component and a near-neighbor, short-range antiferromagnetic component. A detailed magnetic phase diagram has also been constructed which appears to suggest the possibility of a double transition, i.e., a reentrant ferromagnetic to spin-glass transition at low temperature. The experimental data do not support such implied behavior in this system.