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arXiv · 1812.05890

Negative thermal expansion in the plateau state of a magnetically-frustrated spinel

L. Rossi·A. Bobel·S. Wiedmann·R. Küchler·Y. Motome·K. Penc·N. Shannon·H. Ueda·B. Bryant
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Abstract

We report on negative thermal expansion (NTE) in the high-field, half-magnetization plateau phase of the frustrated magnetic insulator CdCr2O4. Using dilatometry, we precisely map the phase diagram at fields of up to 30T, and identify a strong NTE associated with the collinear half-magnetization plateau for B > 27T. 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-localised band of spin excitations in the plateau phase. These results provide useful guidelines for the discovery of new NTE materials.

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L. Rossi, A. Bobel, S. Wiedmann, R. Küchler, Y. Motome, K. Penc, N. Shannon, H. Ueda, B. Bryant. 2018-12-14. Negative thermal expansion in the plateau state of a magnetically-frustrated spinel. https://doi.org/10.1103/physrevlett.123.027205

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