Authors: Desirée S Rausch, Markus Thiemann, Martin Dressel , Daniel Bothner, Dieter Koelle, Reinhold Kleiner and Marc Scheffler
J. Phys. D: Appl. Phys. 51 (2018) 465301
We demonstrate the operation of superconducting coplanar microwave resonators in a very large frequency range up to 50 GHz. The resonators are fabricated from niobium thin films on sapphire substrates and have fundamental frequencies of 5 GHz or 10 GHz. We study numerous harmonics of the resonators at temperatures between 1.5 K and 6 K, and we determine quality factors of up to 22 600 at 1.5 K. As an example for spectroscopy applications of such resonators we detect the superconducting transition of a bulk tin sample at multiple probing frequencies.