Larger in-plane upper critical field and superconducting diode effect observed in topological superconductor candidate InNbS₂ nanoribbons

Recently, the coexistence of topology and superconductivity has garnered considerable attention. Specifically, the dimensionality of these materials is crucial for the realization of topological quantum computation. However, the naturally grown materials, especially with one-dimensional feature that exhibits the coexistence of topology and superconductivity, still face challenges in terms of experimental realization and scalability, which hinders the fundamental research development and the potential to revolutionize quantum computing. Here, we report the first experimental synthesis of quasi-one-dimensional InNbS₂ nanoribbons that exhibit the coexistence of topological order and superconductivity via a chemical vapor transport method. Especially, the in-plane upper critical field of InNbS₂ nanoribbons exceeds the Pauli paramagnetic limit by more than 2.2 times, which can be attributed to the enhanced spin-orbit coupling and the weakened interlayer interaction between the NbS₂ layers induced by the insertion of In atoms, making InNbS₂ exhibit spin-momentum locking similar to that of monolayer NbS₂. Moreover, for the first time, we report the superconducting diode effect in a quasi-one-dimensional superconductor system without any inherent geometric imperfections. The measured maximum efficiency is manifested as 14%, observed at μ₀H ≈ ±60 mT, and we propose that the superconducting diode effect can potentially be attributed to the presence of the nontrivial topological band. Our work provides a platform for studying exotic phenomena in condensed matter physics and potential applications in quantum computing and quantum information processing.