Spin-triplet superconductivity in K(2)Cr(3)As(3)

A spin-triplet superconductor can harbor Majorana bound states that can be used in topological quantum computing. Recently, K(2)Cr(3)As(3) and its variants with critical temperature T(c) as high as 8 kelvin have emerged as a new class of superconductors with ferromagnetic spin fluctuations. Here, we report a discovery in K(2)Cr(3)As(3) single crystal that the spin susceptibility measured by (75)As Knight shift below T(c) is unchanged with the magnetic field H(0) applied in the ab plane but vanishes toward zero temperature when H(0) is along the c axis, which unambiguously establishes this compound as a spin-triplet superconductor described by a vector order parameter [Formula: see text] parallel to the c axis. Combining with point nodal gap, we show that K(2)Cr(3)As(3) is a new platform for the study of topological superconductivity and its possible technical application.