Negative Thermal Expansion in the Plateau State of a Magnetically Frustrated Spinel.
PHYSICAL REVIEW LETTERS 2019;
123:027205. [PMID:
31386536 DOI:
10.1103/physrevlett.123.027205]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 04/04/2019] [Indexed: 06/10/2023]
Abstract
We report on negative thermal expansion (NTE) in the high-field, half-magnetization plateau phase of the frustrated magnetic insulator CdCr_{2}O_{4}. Using dilatometry, we precisely map the phase diagram at fields of up to 30 T and identify a strong NTE associated with the collinear half-magnetization plateau for B>27 T. The resulting phase diagram is compared with a microscopic theory for spin-lattice coupling, and the origin of the NTE is identified as a large negative change in magnetization with temperature, coming from a nearly localized band of spin excitations in the plateau phase. These results provide useful guidelines for the discovery of new NTE materials.
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