Rossi L, Bobel A, Wiedmann S, Küchler R, Motome Y, Penc K, Shannon N, Ueda H, Bryant B
High Field Magnet Laboratory (HFML-EMFL), Radboud University, 6525 ED Nijmegen, Netherlands.
Institute of Molecules and Materials, Radboud University, 6525 AJ Nijmegen, Netherlands.
Phys Rev Lett. 2019 Jul 12;123(2):027205. doi: 10.1103/PhysRevLett.123.027205.
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.
我们报道了受挫磁绝缘体CdCr₂O₄在高场半磁化平台相中的负热膨胀（NTE）现象。利用膨胀测量法，我们精确绘制了高达30 T磁场下的相图，并确定在B>27 T时，与共线半磁化平台相关的强烈NTE。将所得相图与自旋 - 晶格耦合的微观理论进行了比较，NTE的起源被确定为磁化强度随温度的大幅负变化，这源于平台相中自旋激发的近局域能带。这些结果为发现新型NTE材料提供了有用的指导。
