Physics Department - Observation of Spin-triplet Superconductivity in Nonmagnetic CoSi2/TiSi2 Heterojunctions

Abstract

Unconventional superconductivity, particularly spin-triplet superconductivity, has been attractive for topological materials and quantum technology research. I present our recent observations of triplet pairing symmetry in nonmagnetic CoSi2/TiSi2 heterostructures. CoSi2 films grown on silicon undergo a sharp superconducting transition at a critical temperature of about 1.5 K, while TiSi2 is a diffusive normal metal. We investigate the phase-sensitive conductance spectra using two independent and complementary types of superconductor/normal metal (S/N) heterostructures, i.e., the CoSi2/TiSi2 S/N junctions and “T-shaped superconducting proximity structures” with a highly transparent S/N interface [1, 2]. In both cases and the superconducting state, we have found extraordinary zero-bias conductance peaks and signatures that point to two-component (s- + p-wave) superconductivity with a dominant spin-triplet p-wave superconducting pairing component. I also discuss the unusual normal-state electrical-transport properties of CoSi2 films on silicon, which reveal strong Rashba spin-orbit coupling [3]. I shall propose that the microfabrication of CoSi2/TiSi2 heterostructures is fully compatible with the present-day silicon-based integrated-circuit technology, allowing the scalability of potential superconducting devices and quantum circuits.

References
[1] Chiu S. P., et al., Science Advances 7, eabg6569 (2021)
[2] Chiu S. P., et al., Nanoscale 15, 9179 (2023)
[3] Chiu S. P., et al., Chinese Journal of Physics 90, 348 (2024)