Glassy dynamics in magnetization across the first order ferromagnetic to antiferromagnetic transitionin Fe0.955Ni0.045Rh

Abstract

We present the results of magnetization relaxation measurementsacross the ferromagnetic to antiferromagnetic transition inFe0.955Ni0.045Rh. The transition from the high temperature ferromagnetic phase to the low temperatureantiferromagnetic phase seems to be arrested by increasing the applied magnetic field. Thecrossover from crystallization-like dynamics to glassy dynamics can be tracked bymeasuring isothermal time dependent magnetization at various constant temperatureswhile cooling across this ferromagnetic to antiferromagnetic transition. The initialconversion from the ferromagnetic to antiferromagnetic phase as a function of time athigher temperatures follows a distinct power law relaxation. The transition is incomplete atlow temperatures with the stretched exponential relaxation behaviour dominating over thepower law, which is indicative of glassy dynamics or the arrest of the kinetics of the phasetransition. In the intermediate temperature regime, the magnetic relaxation can beexplained as a combination of both the power law and stretched exponential. Thetemperature dependence of the time constant of the stretched exponential follows theArrhenius law which is usually observed in the case of strong glass-forming liquids.