Exploring Non-Linear Kinetic Inductance in Disordered Superconducting NbN thin films

Understanding high kinetic inductance superconducting materials is crucial due to their promising applications in quantum technologies that demand magnetic field and temperature resilience at microwave frequencies [1]. In this presentation, I will provide an overview of our research on non-linear kinetic inductance circuits based on superconducting disordered niobium nitride (NbN) films where we characterize DC and AC-current-biased microwave resonators fabricated from a thin film (∼ 10 nm) exhibiting high kinetic inductance (∼ 50 pH/sq). To begin with, we investigate the nonlinearity of the NbN kinetic inductance by measuring the frequency dependence of our resonators at GHz frequencies [1]. Furthermore, we extract the depairing current of the NbN layer through its magnetic field critical temperature dependence at DC current [2]. Finally, we compare both quantities in the light of Usadel equations [3][4] and show a direct link between them.

[1] C. Yu et al, Appl. Phys. Lett. 118, 054001 (2021).

[2] A. Anthore et al, Phys. Rev. Lett. 90, 127001 (2003).

[3] J. R. Clem et al, Phys. Rev. B. 86, 174521 (2012).

[4] S. Frasca et al, Phys. Rev. B. 100, 054520 (2019).