Observation of triplet superconductivity in CoSi2/TiSi2 heterostructures
Abstract
Unconventional superconductivity and in particular triplet superconductivity have been front and center of topological materials and quantum technology research. Here we report our observation of triplet superconductivity in nonmagnetic CoSi2/TiSi2 heterostructures on silicon. CoSi2 undergoes a sharp superconducting transition at a critical temperature Tc ≈ 1.5 K, while TiSi2 is a normal metal. We investigate conductance spectra of both two-terminal CoSi2/TiSi2 tunnel junctions and three-terminal T-shaped CoSi2/TiSi2 superconducting proximity structures. We report an unexpectedly large spin-orbit coupling in CoSi2 heterostructures. Below Tc, we observe (1) a narrow zero-bias conductance peak on top of a broad hump, accompanied by two symmetric side dips in the tunnel junctions, (2) a narrow zero-bias conductance peak in T-shaped structures, and (3) hysteresis in the junction magnetoresistance. These three independent and complementary observations are indicative of chiral p-wave pairing in CoSi2/TiSi2 heterostructures. This chiral triplet superconductivity and the excellent fabrication compatibility of CoSi2 and TiSi2 with present-day silicon integrated-circuit technology facilitate full scalability for potential use in quantum-computing devices.