- Editors' Suggestion
- Letter
Observation of plasma excitations of superconducting electrons in NbN thin films
Phys. Rev. B 113, L100503 – Published 31 March, 2026
DOI: https://doi.org/10.1103/crcr-w98q
Abstract
In the present work we report the observations of two-dimensional plasma resonance with linear dispersion in superconducting NbN films fabricated by atomic layer deposition on sapphire and high-resistive silicon substrates. We have detected several consecutive resonance dips in terahertz transmission of the sample processed into the disk geometry. Increasing temperature results both in the pronounced shifts of their resonant frequencies and their broadening. Above the critical temperature of superconducting phase transition these features vanish. Both the linear dispersion of these features and their temperature evolution allows us to attribute these resonances to the collective plasma modes in a two-component electron system. Dispersion of these plasmonic excitations showed linear dependence, similar to the theoretical prediction calculated for the two-component system consisting of Cooper pairs and normal electrons.
