Electronic and superconducting properties of CoSi2 films on silicon — An unconventional superconductor with technological potential

We report observations of unusual normal-state electronic conduction properties and superconducting characteristics of high-quality CoSi2/Si films grown on silicon Si(100) and Si(111) substrates.A good understanding of these features shall help to address the underlying physics of the unconventional pairing symmetry recently observed in transparent CoSi2/TiSi2 heterojunctions [S.P. Chiu et al., Sci.Adv. 7, eabg6569 (2021); Nanoscale 15, 9179 (2023)], where CoSi2/Si is a superconductor with a superconducting transition temperature Tc ≃ (1.1-1.5)K, dependent on its dimensions, and TiSi2 is a normal metal.In CoSi2/Si films, we find a pronounced positive magnetoresistance caused by the weak-antilocalization effect, indicating a strong Rashba spin-orbit coupling (SOC).This SOC generates two-component superconductivity in CoSi2/TiSi2 heterojunctions.The CoSi2/Si films are stable under ambient conditions and have ultralow 1/f noise.Moreover, they can be patterned via the standard lithography techniques, which might be of considerable practical value for future scalable superconducting and quantum device fabrication.