Search for: All records

A localized Zeeman field, intensified at heterostructure interfaces, could play a crucial role in a broad area including spintronics and unconventional superconductors. Conventionally, the generation of a local Zeeman field is achieved through magnetic exchange coupling with a magnetic material. However, magnetic elements often introduce defects, which could weaken or destroy superconductivity. Alternatively, the coupling between a superconductor with strong spin-orbit coupling and a nonmagnetic chiral material could serve as a promising approach to generate a spin-active interface. Here, we leverage an interface superconductor, namely, induced superconductivity in noble metal surface states, to probe the spin-active interface. Our results unveil an enhanced interface Zeeman field, which selectively closes the surface superconducting gap while preserving the bulk superconducting pairing. The chiral material, i.e., trigonal tellurium, also induces Andreev bound states (ABS) exhibiting spin polarization. The field dependence of ABS manifests a substantially enhanced interface Landég-factor (g_eff~ 12), thereby corroborating the enhanced interface Zeeman energy. 

A fully-functional photonic integrated circuit (PIC) platform with supporting active and passive components in the extended short- and mid-wave infrared spectral regime is of significant research interest for next-generation optical systems. Here we design offset quantum well-based photonic integrated circuits which primarily consist of four section-based widely tunable single-mode lasers emitting at 2560 nm. The platform requires the selective removal of InGaAsSb multi-quantum wells located above a GaSb-based optical waveguide layer and then subsequent single blanket GaSb regrowth. Encouraging preliminary experimental results on regrowth are also reported to confirm the feasibility of the proposed PICs. The simulation result for the tunable laser design shows that a tuning range as wide as ~120 nm is possible. The quasi-theoretical work performed here is an initial step towards demonstrating complex non-telecommunication PICs which could offer a comprehensive range of photonic functionalities.