Phase coexistence and negative thermal expansion in the triple perovskite iridate Ba3CoIr2O9

Charu Garg, Antonio Cervellino, and Sunil Nair
Phys. Rev. Materials 5, 044405 – Published 16 April 2021

Abstract

The anomalous thermal expansion in a layered 3d5d based triple perovskite iridate Ba3CoIr2O9 is investigated using high resolution synchrotron diffraction. Below the magnetostructural transition at 107 K, the onset of antiferromagnetic order is associated with a monoclinic distortion of the hexagonal structure. Deeper within the magnetically ordered state, a part of the monoclinic phase distorts even further, and both these structural phases co-exist down to the lowest measured temperatures. We observe negative thermal expansion in this phase co-existence regime, which appears to be intimately connected to the temperature driven relative fractions of these monoclinic phases. The significant NTE observed in this system could be driven by magnetic exchange striction and is of relevance to a number of systems with pronounced spin orbit interactions.

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  • Received 9 October 2020
  • Revised 24 February 2021
  • Accepted 5 April 2021

DOI:https://doi.org/10.1103/PhysRevMaterials.5.044405

©2021 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Charu Garg1, Antonio Cervellino2, and Sunil Nair1,*

  • 1Department of Physics, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune 411008, India
  • 2Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen, Switzerland

  • *sunil@iiserpune.ac.in

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Vol. 5, Iss. 4 — April 2021

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