Abstract Within the RCo2 family of compounds, a structural distortion linked with the onset of magnetic ordering around the critical temperature can be observed. One of the less explored RCo2 compounds is TmCo2 probably due to its low Curie temperature. Exceptionally this compound, given its position at the end of the ferrimagnetic series, shows discrepancies in the ordering of the Co sub-lattice because of a weak Weiss molecular field. In this paper we focus on the structural distortion in TmCo2, which appears together with the magnetic ordering around the critical temperature of T C ∼ 3.6 K. Poly-crystals as well as single-crystals of TmCo2 were used in our experiments. For both kinds of samples we observed the same type of the rhombohedral distortion along the [111] direction from the cubic Fd 3 ¯ m to R 3 ¯ m space group. The relation between observed magnetic and structural properties in this compound is discussed.

中文翻译：

---

TmCo2 中的晶格畸变：多晶和单晶研究

摘要 在 RCo2 化合物家族中，可以观察到与临界温度附近磁有序开始相关的结构畸变。研究较少的 RCo2 化合物之一是 TmCo2，可能是由于其居里温度低。由于 Weiss 分子场较弱，该化合物位于亚铁磁系列的末端，在 Co 亚晶格的排序中显示出差异。在本文中，我们关注 TmCo2 的结构畸变，它与 TC ～ 3.6 K 临界温度附近的磁有序一起出现。我们的实验中使用了 TmCo2 的多晶和单晶。对于这两种样品，我们沿 [111] 方向从立方 Fd 3 ¯ m 到 R 3 ¯ m 空间群观察到相同类型的菱形畸变。