Cooperative Cluster Jahn-Teller Effect as a Possible Route to Antiferroelectricity

K. Geirhos, J. Langmann, L. Prodan, A. A. Tsirlin, A. Missiul, G. Eickerling, A. Jesche, V. Tsurkan, P. Lunkenheimer, W. Scherer, and I. Kézsmárki
Phys. Rev. Lett. 126, 187601 – Published 4 May 2021
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Abstract

We report the observation of an antipolar phase in cubic GaNb4S8 driven by an unconventional microscopic mechanism, the cooperative Jahn-Teller effect of Nb4S4 molecular clusters. The assignment of the antipolar nature is based on sudden changes in the crystal structure and a strong drop of the dielectric constant at TJT=31K, also indicating the first-order nature of the transition. In addition, we found that local symmetry lowering precedes long-range orbital ordering, implying the presence of a dynamic Jahn-Teller effect in the cubic phase above TJT. Based on the variety of structural polymorphs reported in lacunar spinels, also including ferroelectric phases, we argue that GaNb4S8 may be transformable to a ferroelectric state, which would further classify the observed antipolar phase as antiferroelectric.

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  • Received 16 September 2020
  • Revised 2 March 2021
  • Accepted 8 April 2021

DOI:https://doi.org/10.1103/PhysRevLett.126.187601

© 2021 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

K. Geirhos1, J. Langmann2, L. Prodan1,3, A. A. Tsirlin4, A. Missiul5, G. Eickerling2, A. Jesche4, V. Tsurkan1,3, P. Lunkenheimer1, W. Scherer2, and I. Kézsmárki1

  • 1Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, 86135 Augsburg, Germany
  • 2CPM, Institute of Physics, University of Augsburg, 86135 Augsburg, Germany
  • 3Institute of Applied Physics, MD 2028, Chisinau, Republic of Moldova
  • 4Experimental Physics VI, Center for Electronic Correlations and Magnetism, University of Augsburg, 86135 Augsburg, Germany
  • 5CELLS-ALBA Synchrotron, Cerdanyola del Valles, E-08290 Barcelona, Spain

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Issue

Vol. 126, Iss. 18 — 7 May 2021

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