Observation of charge–transfer–driven antiferroelectricity in 3d-pyrochlore multiferroic Cu 2 OCl 2

H. C. Wu, J. K. Yuan, K. D. Chandrasekhar, C. H. Lee, W. H. Li, C. W. Wang, J. M. Chen, Jiunn-Yuan Lin, H. Berger, T. W. Yen, S. M. Huang, C. W. Chu, H. D. Yang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Very recently, multiferroic behavior close to the boiling temperature of liquid nitrogen was reported in oxohalide-based Cu 2 OCl 2 . In this study, we have established yet another novel mechanism for the origin of charge ordering in multiferroic Cu 2 OCl 2 . The direct current (DC) magnetization, specific heat, and neutron diffraction measurements confirm the antiferromagnetic (AFM) ordering (T N ) of Cu 2 OCl 2 near 70 K. The collinear AFM spin structure in Cu 2 OCl 2 was obtained from neutron powder diffraction experiments based on the fitting to the combination of two irreducible representations—Г 1 ⊕Г 2. Electrical properties, such as dielectric constant, pyroelectric current, and polarization-electric field hysteresis-loop measurements, together suggest a long-range antiferroelectric ordering near T E ≈ 75 K. The charge transfer from Cl to O along the c-axis was found to induce antiferroelectricity near T E and is supported from ab initio calculations. This finding largely reduces the possibility of well-known Dzyaloshinskii–Moriya interaction in the observed multiferroic behaviors and provides insight into the various origins of high-T C multiferroics.

Original languageEnglish
Pages (from-to)34-42
Number of pages9
JournalMaterials Today Physics
Volume8
DOIs
StatePublished - 1 Mar 2019

Keywords

  • Charge ordering
  • Collinear spin structure
  • Geometrical spin-frustration
  • Multiferroicity
  • Pyrochlore structure
  • Structural distortion

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