Monoclinic EuSn2As2 : A Novel High-Pressure Network Structure
| Autor: | Changjiang Yi, Zhenhua Chi, Youguo Shi, Lin Zhao, Xiaoli Ma, Jianhong Dai, Jinguang Cheng, Binbin Yue, Jian-Tao Wang, Xiaohui Yu, Yonghao Han, Chang-Tian Wang, Yunyu Yin, Pengtao Yang, Fang Hong |
|---|---|
| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | Physical Review Letters. 126 |
| ISSN: | 1079-7114 0031-9007 |
| DOI: | 10.1103/physrevlett.126.155701 |
| Popis: | The layered crystal of ${\mathrm{EuSn}}_{2}{\mathrm{As}}_{2}$ has a ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$-type structure in rhombohedral ($R\overline{3}m$) symmetry and has been confirmed to be an intrinsic magnetic topological insulator at ambient conditions. Combining ab initio calculations and in situ x-ray diffraction measurements, we identify a new monoclinic ${\mathrm{EuSn}}_{2}{\mathrm{As}}_{2}$ structure in $C2/m$ symmetry above $\ensuremath{\sim}14\text{ }\text{ }\mathrm{GPa}$. It has a three-dimensional network made up of honeycomblike Sn sheets and zigzag As chains, transformed from the layered ${\mathrm{EuSn}}_{2}{\mathrm{As}}_{2}$ via a two-stage reconstruction mechanism with the connecting of Sn-Sn and As-As atoms successively between the buckled SnAs layers. Its dynamic structural stability has been verified by phonon mode analysis. Electrical resistance measurements reveal an insulator-metal-superconductor transition at low temperature around 5 and 15 GPa, respectively, according to the structural conversion, and the superconductivity with a ${T}_{C}$ value of $\ensuremath{\sim}4\text{ }\text{ }\mathrm{K}$ is observed up to 30.8 GPa. These results establish a high-pressure ${\mathrm{EuSn}}_{2}{\mathrm{As}}_{2}$ phase with intriguing structural and electronic properties and expand our understandings about the layered magnetic topological insulators. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|