Signature of Quantum Phase Slips in a Layered Quasi-One-Dimensional Nb₂PdS₅ Superconductor

Quantum phase slips (QPSs) have emerged as a key mechanism driving the breakdown of superconductivity in one-dimensional (1D) systems, especially under strong quantum fluctuations and disorder. In this context, we report the observation of a quantum phase slip event in quasi-1D Nb2PdS5 nanowires. Our findings reveal that as the wire width is reduced below the magnetic penetration depth, the superconducting transition (Tc) broadens significantly, a behavior that aligns well with the QPS theoretical model. The temperature-dependent resistance under magnetic fields applied perpendicular and parallel to the applied current (b-axis) of the Nb2PdS5 nanowire device shows the highest upper critical field (Bc2) at around 73.3 T for B//I. The upper critical field Bc2 exhibits strong anisotropy and exceeds the Pauli limit (BpBCS ≈ 11.96 T) under parallel magnetic fields, which is consistent with the enhanced role of QPSs. Current–voltage (I–V) characteristics reveal discrete voltage steps during the superconducting transition to the normal state, further confirming the occurrence of the QPS event in the quasi-1D superconducting system. The reduction in critical current Ic with decreasing wire width provides an experimental signature of the QPS.