Resistance fluctuation spectroscopy of phase transitions in (La0.2Pr0.2Nd0.2Sm0.2Eu0.2)NiO3 thin films

Abstract

The study of phase transitions is crucial to understanding the physics of materials and utilizing them for technological applications. This article presents a detailed analysis of the electronic transport properties of high entropy oxide thin films. We observe an increase in resistance fluctuations across a first-order phase transition. We show that the noise arises from an electronic phase separation accompanying the spin ordering due to the formation of domains of localized and delocalized charges. We conclude that due to charge disproportionation, the charge carriers form domains of localized and delocalized electrons in this system. Our study establishes the existence of multiple states with near equal energy in such complex oxide thin films.

Electronic Noise Spectroscopy of Quasi-Two-Dimensional Antiferromagnetic Semiconductors

“…At the transition point, the material system can fluctuate between the two phases, acting as a two-level system (TLS). The magnetic phase transition is observed in many magnetic materials, characterized by a two-level resistance state. − The two-level system can also be related to the discrete fluctuations associated with the RTS noise . The RTS noise appears in the time domain as pulses with uniform amplitude but random pulse widths and intervals.…”

“…Since it appears only close to the magnetic phase transition at ∼118 K and disappears in the PM phase, it is evident that the Lorentzian component is associated with the magnetic phase transition and subsequent subtle change in its resistive behavior, as shown in Figure d. The nature of noise spectra is generally affected by the change in material phases in terms of electrical, structural, and magnetic properties. ,, When the material undergoes a phase change, the noise behavior can appear in the Lorentzian form due to the creation of a two-level system. In our case, at 118 K, the material undergoes a transition from the PM to the AFM phase.…”