Slow dynamics in hard condensed matter: a case study of the phase separating system NdNiO₃

Abstract

We report the time dependent response of electrical resistivity in the non-magnetic perovskite oxide NdNiO(3) in its phase separated state and provide a physical explanation of the observations. We also model the system and make an accurate Monte Carlo simulation of the observed behavior. While cooling, a phase separation takes place in the system below its metal-insulator transition temperature and in this state the material exhibits various dynamical phenomena such as relaxation of resistivity, dependence of resistivity on cooling rate and rejuvenation of the material after ageing. These phenomena signal that the phase separated state of NdNiO(3) is not in thermodynamic equilibrium, and we conjecture that it consists of supercooled paramagnetic metallic and antiferromagnetic insulating phases. The supercooled phases are metastable and they switch over to the insulating equilibrium state stochastically, and this can account for the slow dynamics observed in our system. We also verify the predictive power of our model by simulating the result of a new experiment and confirming it by actual measurements.

Heterogeneous nucleation and metal-insulator transition in epitaxial films of NdNiO3

“…See inset of figure 3 and Ref. 8). No detectable time dependence was observed below 95 K and in the subsequent heating run.…”

“…This in turn results in a hysteresis between cooling and heating data. 8,9 In this paper we report time and temperature dependent resistivity measurements on thin films of the FOPT system NdNiO 3 and has compared the results with the bulk. Our results show that the M-I transition in the bulk is associated with a large hysteresis and strong dynamical effects while in thin films it has a small hysteresis and weak dynamical effects.…”

Contrasting effects of doping on insulating and metallic states of NdNi1−xMnxO3 thin films

“…This hysteresis originates from thermodynamically unstable state, which also gives rise to time-dependent resistivity. 21 Basically, the nucleation of metallic/insulating clusters is inhomogeneous while cooling/heating, which results into resistivity-hysteresis. 14,22 We find that Mn-doping has a direct relation with the observed thermal hysteresis of resistivity, as explained below.…”

“…The values of activation energy are comparable to those reported earlier. 21,22,24 A wider range of data fit to VRH model compared to activation type behavior at low temperature. As indicated by these fittings, the transport is taking place through hopping of charge carriers in NNMO/NGO (x ¼ 0.10) and NNMO/YAO (x ¼ 0.10) thin films at low temperatures (Fig.…”

Electrical Transport in Ultrathin NdNiO3 Films

“…The 6 nm thick sample Based on this time dependent data, the structural behavior of NdNiO 3 at low temperatures can be inferred. It is proposed that the 1.2 nm sample transitions to a kinetically arrested glassy state, with little supercooling [19,20]. As the temperature was decreased, the metallic state supercooled slightly, with most of this state directly forming the glassy state.…”