Observation of insulator-metal transition in EuNiO$_{3}$ under high pressure

TL;DR

This study demonstrates that applying high pressure to EuNiO₃ induces an insulator-metal transition at 5.8 GPa, accompanied by changes in magnetic order, without altering its orthorhombic crystal structure.

Contribution

It provides experimental evidence of pressure-induced insulator-metal transition in EuNiO₃ and elucidates the role of bandwidth increase in this process, with detailed magnetic and structural analysis.

Findings

Insulator-metal transition occurs at 5.8 GPa.

Metallic state exhibits magnetic order with reduced T_N.

Orthorhombic structure remains stable up to 20 GPa.

Abstract

The charge transfer antiferromagnetic (T$_{N}$ =220 K) insulator EuNiO$_{3}$ undergoes, at ambient pressure, a temperature-induced metal insulator MI transition at T$_{MI}$=463 K. We have investigated the effect of pressure (up to p~20 GPa) on the electronic, magnetic and structural properties of EuNiO$_{3}$ using electrical resistance measurements, ${151}^$Eu nuclear resonance scattering of synchrotron radiation and x-ray diffraction, respectively. With increasing pressure we find at p$_{c}$ =5.8 GPa a transition from the insulating state to a metallic state, while the orthorhombic structure remains unchanged up to 20 GPa. The results are explained in terms of a gradual increase of the electronic bandwidth with increasing pressure, which results in a closing of the charge transfer gap. It is further shown that the pressure-induced metallic state exhibits magnetic order with a lowervalue of T$_{N}$ (T$_{N}$ ~120 K at 9.4 GPa) which disappears between 9.4 and 14.4 GPa.