Single crystals of NbGe2 which crystallize in a noncentrosymmetric hexagonal structure with chirality are synthesized and their superconductivity is investigated. Type-I superconductivity is confirmed by dc magnetization, field-induced second-to first-order phase transition in specific heat, and a small Ginzburg-Landau parameter κGL=0.12. The isothermal magnetization measurements show that there is a crossover from type-I to type-II/1 superconductivity with decreasing temperature and an unusually enhanced surface superconducting critical field (Hc3) is discovered. The band structure calculations indicate the presence of Kramer-Weyl nodes near the Fermi level. These observations demonstrate that NbGe2 is an interesting and rare example involving the possible interplay of type-I superconductivity, noncentrosymmetric structure and topological properties.
@article{arxiv.2008.10841,
title = {Type-I superconductivity in noncentrosymmetric NbGe$_{2}$},
author = {Baijiang Lv and Miaocong Li and Jia Chen and Yusen Yang and Siqi Wu and Lei Qiao and Feihong Guan and Hui Xing and Qian Tao and Guang-Han Cao and Zhu-An Xu},
journal= {arXiv preprint arXiv:2008.10841},
year = {2020}
}