Type-I superconductivity in the Weyl semimetal TaGe 2 with chiral structure

作者：Zhou Li, Wenwen Yang, Junjie Feng, Bin-Bin Ruan, Yazhou Zhou, Tao Sun, Hongwei Shi, Le Ju, Suo-Fu Wang, Tao Han, Jiang-Peng Song, Xianyi Hu, Zekun Zhou, Mingsheng Long, Xingyuan Hou, Qingdong Xu, Zhi-An Ren, Qing-Ge Mu, Lei Shan · 发表于：Physical review. B./Physical review. B · 年份：2024 · DOI：10.1103/physrevb.110.174506 · 被引用次数：5 · 研究领域：Iron-based superconductors research、Topological Materials and Phenomena、Rare-earth and actinide compounds

Nonmagnetic chiral crystals host Kramers-Weyl fermions at time-inversion invariant momenta and can exhibit a topological nontrivial Fermi surface. Exploring topological superconductivity in chiral materials is thus an area of active research. In this study, we have successfully grown high-quality single crystals of ${\mathrm{TaGe}}_{2}$ which adopt a chiral hexagonal lattice structure. We conducted comprehensive experimental measurements on superconductivity, complemented by theoretical calculations. Magnetic property, electrical resistivity, and heat capacity data indicate that ${\mathrm{TaGe}}_{2}$ undergoes a type-I superconducting transition at 1.9 K. Further analysis of low-temperature heat capacity data suggest that ${\mathrm{TaGe}}_{2}$ is a weakly coupled single-band BCS superconductor. We constructed a phase diagram of critical field obtained by heat capacity and electrical resistivity measurements. Surface superconductivity was observed in this type-I superconductor with a \ensuremath{\kappa} value of 0.074, and the ratio of surface critical field $({\ensuremath{\mu}}_{0}{H}_{\mathrm{s}})$ to the bulk critical field $({\ensuremath{\mu}}_{0}{H}_{\mathrm{c}})$ is remarkably high. Our density functional theory calculations identified two independent Weyl points near Fermi level besides the Kramers-Weyl nodes, which may contribute to the unusual critical field behavior. These findings demonstrate that ${\mathrm{TaGe}}_{2}$ is a promising material for exploring the inter...