Tracking spin-glass barriers versus field and temperature ina-Gd0.19Si0.81

Abstract

Detailed signatures of the states of the low-temperature spin-glass phase in a-GdSi films were followed using resistance fluctuations. Two-state switches between different spin-glass configurations were unambiguously identified by the field dependences of the occupation ratios of the states. The temperature dependences of the rates and occupation ratios were tracked in order to determine thermodynamic parameters of the switchers and the temperature dependences of barriers. A reasonable distribution of energy and entropy differences between states was found. Most importantly, the kinetic barriers were found to show no sign of divergence with lowering temperature, contrary to expectations based on prior theoretical and experimental works.

Effects of Co doping on the metamagnetic states of the ferromagnetic fcc Fe–Co alloy

“…Indeed, it would be safe to assume that this system exhibits the behavior called by Moruzzi [18] 'spin glass', which in the present work we denote as 'degenerate metamagnetic states'. A system with degenerate metamagnetic states results in E HS = E LS , such that alloys around x = 0.05 may exhibit switching of spin configurations between different metastable states [86], which can be characterized by the low-temperature noise resistance fluctuations technique [86][87][88].…”