Yang Jie, Luo Jun, Yi Changjiang, Shi Youguo, Zhou Yi, Zheng Guo-Qing
Institute of Physics, Chinese Academy of Sciences and Beijing National Laboratory for Condensed Matter Physics, Beijing 100190, China.
Kavli Institute for Theoretical Sciences, CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China.
Sci Adv. 2021 Dec 24;7(52):eabl4432. doi: 10.1126/sciadv.abl4432. Epub 2021 Dec 22.
A spin-triplet superconductor can harbor Majorana bound states that can be used in topological quantum computing. Recently, KCrAs and its variants with critical temperature as high as 8 kelvin have emerged as a new class of superconductors with ferromagnetic spin fluctuations. Here, we report a discovery in KCrAs single crystal that the spin susceptibility measured by As Knight shift below is unchanged with the magnetic field applied in the plane but vanishes toward zero temperature when is along the axis, which unambiguously establishes this compound as a spin-triplet superconductor described by a vector order parameter parallel to the axis. Combining with point nodal gap, we show that KCrAs is a new platform for the study of topological superconductivity and its possible technical application.
自旋三重态超导体可以容纳可用于拓扑量子计算的马约拉纳束缚态。最近，临界温度高达8开尔文的KCrAs及其变体已成为一类具有铁磁自旋涨落的新型超导体。在此，我们报告在KCrAs单晶中的一项发现：在低于[某个温度值]时，通过砷核自旋弛豫率测量的自旋磁化率，在沿平面施加磁场时不随磁场变化，但当磁场沿轴时，随着温度趋近于零而消失，这明确地将该化合物确定为一种由平行于轴的矢量序参量描述的自旋三重态超导体。结合点节点能隙，我们表明KCrAs是研究拓扑超导及其可能的技术应用的一个新平台。
