Observation of triplet superconductivity in CoSi2/TiSi2 heterostructures

Tuning interfacial two-component superconductivity in CoSi2/TiSi2 heterojunctions via TiSi2 diffusivity

We report the observation of enhanced interfacial two-component superconductivity possessing a dominant triplet component in nonmagnetic CoSi₂/TiSi₂ superconductor/normal-metal planar heterojunctions. This is accomplished through the detection of odd-frequency spin-triplet even-parity Cooper pairs in the diffusive normal-metal component of T-shaped proximity junctions. We show that by modifying the diffusivity of the normal-metal part, the transition temperature enhancement can be tuned by a factor of up to 2.3 while the upper critical field increases by up to a factor of 20. Our data suggest that the C49 phase of TiSi₂, which is stabilized in confined geometries, underlies this enhancement. These findings are addressed via a Ginzburg-Landau model and the quasi-classical theory. We also relate our findings to the enigmatic 3-K phase reported in Sr₂ RuO₄.

Suppressing Andreev Bound State Zero Bias Peaks Using a Strongly Dissipative Lead

Hybrid semiconductor-superconductor nanowires are predicted to host Majorana zero modes that induce zero-bias peaks (ZBPs) in tunneling conductance. ZBPs alone, however, are not sufficient evidence due to the ubiquitous presence of Andreev bound states. Here, we implement a strongly resistive normal lead in InAs-Al nanowire devices and show that most of the expected Andreev bound state-induced ZBPs can be suppressed, a phenomenon known as environmental Coulomb blockade. Our result is the first experimental demonstration of this dissipative interaction effect on Andreev bound states and can serve as a possible filter to narrow down the ZBP phase diagram in future Majorana searches.