Yu Fanghang, Zhu Xudong, Wen Xikai, Gui Zhigang, Li Zeyu, Han Yulei, Wu Tao, Wang Zhenyu, Xiang Ziji, Qiao Zhenhua, Ying Jianjun, Chen Xianhui
Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, and CAS Key Laboratory of Strongly-coupled Quantum Matter Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
Department of Physics, Fuzhou University, Fuzhou, Fujian 350108, China.
Phys Rev Lett. 2022 Feb 18;128(7):077001. doi: 10.1103/PhysRevLett.128.077001.
The recently discovered kagome superconductors AV_{3}Sb_{5} exhibit tantalizing high-pressure phase diagrams, in which a new domelike superconducting phase emerges under moderate pressure. However, its origin is as yet unknown. Here, we carried out the high-pressure electrical measurements up to 150 GPa, together with the high-pressure x-ray diffraction measurements and first-principles calculations on CsV_{3}Sb_{5}. We find the new superconducting phase to be rather robust and inherently linked to the interlayer Sb2-Sb2 interactions. The formation of Sb2-Sb2 bonds at high pressure tunes the system from two-dimensional to three-dimensional and pushes the p_{z} orbital of Sb2 upward across the Fermi level, resulting in enhanced density of states and increase of T_{C}. Our work demonstrates that the dimensional crossover at high pressure can induce a topological phase transition and is related to the abnormal high-pressure T_{C} evolution. Our findings should apply for other layered materials.
最近发现的 Kagome 超导体 AV₃Sb₅ 展现出诱人的高压相图，其中在中等压力下会出现一个新的穹顶状超导相。然而，其起源尚不清楚。在此，我们对 CsV₃Sb₅ 进行了高达 150 GPa 的高压电学测量，同时进行了高压 X 射线衍射测量和第一性原理计算。我们发现新的超导相相当稳定，并且与层间 Sb₂ - Sb₂ 相互作用有着内在联系。高压下 Sb₂ - Sb₂ 键的形成将体系从二维调制成三维，并推动 Sb₂ 的 p_z 轨道向上穿过费米能级，从而导致态密度增强以及 T_C 升高。我们的工作表明，高压下的维度交叉可以引发拓扑相变，并且与异常的高压 T_C 演化有关。我们的发现应该适用于其他层状材料。
