Pressure-induced unusual metallic state in EuNiO3

Hisao Kobayashi, Shugo Ikeda, Yoshitaka Yoda, Naohisa Hirao, Yasuo Ohishi, J. A. Alonso, M. J. Martinez-Lope, R. Lengsdorf, D. I. Khomskii, and M. M. Abd-Elmeguid
Phys. Rev. B 91, 195148 – Published 28 May 2015

Abstract

The perovskite antiferromagnetic (TN220K) insulator EuNiO3 undergoes at ambient pressure a metal-to-insulator transition at TMI=460K which is associated with a simultaneous orthorhombic-to-monoclinic distortion, leading to charge disproportionation. We have investigated the change of the structural and magnetic properties of EuNiO3 with pressure (up to 20GPa) across its quantum critical point (QCP) using low-temperature synchrotron angle-resolved x-ray diffraction and Eu151 nuclear forward scattering of synchrotron radiation, respectively. With increasing pressure, we find that after a small increase of TN (p2GPa) and the induced magnetic hyperfine field Bhf at the Eu151 nucleus (p9.7GPa), both TN and Bhf are strongly reduced and finally disappear at pc10.5GPa, indicating a magnetic QCP at pc. The analysis of the structural parameters up to 10.5 GPa reveals no change of the lattice symmetry within the experimental resolution. Since the pressure-induced insulator-to-metal transition occurs at pIM6GPa, this result implies the existence of an antiferromagnetic metallic state between 6 and 10.5 GPa. We further show from the analysis of the reported high-pressure electrical resistance data on EuNiO3 at low temperatures that in the vicinity of the QCP the system behaves as non-Fermi-liquid, with the resistance changing as Tn, with n=1.6, whereas it becomes a normal Fermi liquid, n=2, for pressures above 15GPa. On the basis of the obtained data, a magnetic phase diagram in the (p, T) space is suggested.

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  • Received 20 February 2015
  • Revised 28 April 2015

DOI:https://doi.org/10.1103/PhysRevB.91.195148

©2015 American Physical Society

Authors & Affiliations

Hisao Kobayashi* and Shugo Ikeda

  • Graduate School of Material Science and Center for Novel Material Science under Multi-Extreme Conditions, University of Hyogo, Koto Hyogo 678-1297, Japan

Yoshitaka Yoda, Naohisa Hirao, and Yasuo Ohishi

  • Japan Synchrotron Radiation Institute, Hyogo 679-5198, Japan

J. A. Alonso and M. J. Martinez-Lope

  • Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, E-28049 Madrid, Spain

R. Lengsdorf, D. I. Khomskii, and M. M. Abd-Elmeguid

  • II. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany

  • *kobayash@sci.u-hyogo.ac.jp

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Issue

Vol. 91, Iss. 19 — 15 May 2015

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