Observation of triplet superconductivity in CoSi$_2$/TiSi$_2$ heterostructures

TL;DR

This study reports the discovery of triplet superconductivity with chiral p-wave pairing in CoSi₂/TiSi₂ heterostructures on silicon, characterized by unique conductance features and hysteresis, with implications for scalable quantum computing technology.

Contribution

First observation of triplet superconductivity with chiral p-wave pairing in CoSi₂/TiSi₂ heterostructures on silicon, demonstrating potential for quantum device integration.

Findings

Detection of zero-bias conductance peaks indicating triplet pairing

Observation of hysteresis in magnetoresistance

Large spin-orbit coupling in 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 CoSi$_2$/TiSi$_2$ heterostructures on silicon. CoSi$_2$ undergoes a sharp superconducting transition at a critical temperature $T_c \approx$ 1.5 K, while TiSi$_2$ is a normal metal. We investigate conductance spectra of both two-terminal CoSi$_2$/TiSi$_2$ tunnel junctions and three-terminal T-shaped CoSi$_2$/TiSi$_2$ superconducting proximity structures. We report an unexpectedly large spin-orbit coupling in CoSi$_2$ heterostructures. Below $T_c$, 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 CoSi$_2$/TiSi$_2$ heterostructures. This chiral triplet superconductivity and the excellent fabrication compatibility of CoSi$_2$ and TiSi$_2$ with present-day silicon integrated-circuit technology facilitate full scalability for potential use in quantum-computing devices.