Full superconducting gap and type-I to type-II superconductivity transition in single crystalline NbGe2

作     者：Dongting Zhang Tian Le Baijiang Lv Lichang Yin Chufan Chen Zhiyong Nie Dajun Su Huiqiu Yuan Zhu-An Xu Xin Lu 

作者机构：Center for Correlated Matter and Department of Physics Zhejiang University Hangzhou 310058 China Department of Physics Zhejiang University Hangzhou 310027 China Zhejiang Province Key Laboratory of Quantum Technology and Device Zhejiang University Hangzhou 310027 China State Key Laboratory of Silicon Materials Zhejiang University Hangzhou 310027 China Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing 210093 China Zhejiang California International NanoSystems Institute Zhejiang University Hangzhou 310058 China 

出 版 物：《Physical Review B》 (Phys. Rev. B)

年 卷 期：2021年第103卷第21期

页      面：214508-214508页

核心收录：

基　　金：National Natural Science Foundation of China, NSFC, (11374257, 11604291, 11674279, 11774305, 11974306) National Natural Science Foundation of China, NSFC Natural Science Foundation of Zhejiang Province, ZJNSF, (LR18A04001) Natural Science Foundation of Zhejiang Province, ZJNSF National Key Research and Development Program of China, NKRDPC, (2016YFA0300402, 2017YFA0303101) National Key Research and Development Program of China, NKRDPC 

主　　题：Superconducting gap Topological superconductors Andreev point contact spectroscopy 

摘      要：We report a mechanical point-contact spectroscopy study on the single crystalline NbGe2 with a superconducting transition temperature Tc=2.0–2.1 K. The differential conductance curves at 0.3 K can be well fitted by a single-gap s-wave Blonder-Tinkham-Klapwijk model and the temperature-dependent gap follows a standard Bardeen-Cooper-Schrieffer behavior, yielding Δ0∼0.32 meV and 2Δ0/kBTc=3.62 in the weak-coupling limit. In magnetic field, the superconducting gap at 0.3 K remains constant up to Hc1∼150 Oe and gradually decreases until Hc2∼350 Oe, indicating NbGe2 is going through a transition from a type-I to type-II (possible type-II/1) superconductor at low temperature.