Slow Dynamics in Hard Condensed Matter: A Case Study of the Phase Separating System NdNiO$_3$

TL;DR

This study investigates slow, non-equilibrium dynamics in NdNiO$_3$, revealing metastable phase behavior and modeling these phenomena with Monte Carlo simulations, validated by experiments.

Contribution

It provides a detailed physical explanation and a computational model for slow dynamics and phase separation in NdNiO$_3$, a previously less understood phenomenon.

Findings

Resistivity relaxes over time in NdNiO$_3$

Cooling rate affects resistivity behavior

Model accurately predicts experimental results

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 do an accurate Monte Carlo simulation of the observed behavior. While cooling a phase separation takes place in this 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.