Origin of the time dependent effects observed in phase separated systems

Abstract

The phase separated state that is associated with a broad first order electronic phase transition exhibit various dynamic phenomena such as relaxation of resistivity and magnetization, cooling rate dependence, rejuvenation after ageing etc. In the case of magnetic systems, where the coexisting phases are ferro and anti-ferromagnetic, the presence of slow glass-like relaxation has led many authors to treat the phase separated state as a cluster-glass or spin-glass and it has been suggested that the observed time dependent effects are the result of inter-cluster interaction. In this work we report the time dependence resistivity data on the non-magnetic phase separated system, NdNiO3. Our experimental results rule out the possibility of the formation of glassy state. We propose that the dynamical behavior in the phase separated systems has its origin in the presence of high temperature phases in their supercooled state persisting below the first order transition temperature. These supercooled phases are metastable and they switch to the ground state stochastically. We claim that this switching gives rise to time dependent effects in the phase separated regime. We further propose that all the systems which undergo a broad first order transition will exhibit time dependence in their physical properties in the phase separated regime owing at least partially to supercooled to normal switching of the different single phase regions of the material.