Anisotropic superconductivity and elongated vortices with unusual bound states in quasi-one-dimensional nickel-bismuth compounds
Anisotropic superconductivity and elongated vortices with unusual bound states in quasi-one-dimensional nickel-bismuth compounds
We report low-temperature scanning tunneling microscopy and spectroscopy studies of Ni-Bi films grown by molecular beam epitaxy. Highly anisotropic and twofold symmetric superconducting gaps are revealed in two distinct composites, Bi-rich ${\mathrm{NiBi}}_{3}$ and near-equimolar ${\mathrm{Ni}}_{x}\mathrm{Bi}$, both sharing quasi-one-dimensional crystal structure. We further reveal axially elongated vortices in both phases, but …