Determination of the Transition Temperature of a Superconducting Nanowire through its kinetic inductance by coupling to 3D Microwave Cavity Resonator

A thin superconducting nanowire exhibits a broad resistive transition, due to the thermal fluctuations of the superconductor order parameter, namely Little's phase slips. The transition temperature, Tc, extracted from resistive measurements vary depending on the model used, e.g., the LAMH model versus the Little model. We have demonstrated a new method to determine the transition temperature, utilizing a 3D cavity resonator and the property of the wire kinetic inductance to saturate at Tc. A MoGe nanowire was placed in the microwave cavity and the transmission characteristics were probed as a function of temperature and microwave power. The transition temperatures obtained by this method were compared with DC transport data and confirmed that Little's model provides more accurate predictions for the Tc compared to LAMH.