We have looked into cobalt disilicide (CoSi2) as a potential building block for superconducting quantum circuits. In order to achieve this, we annealed a thin layer of Co to create 10-105 nm thick microwave cavities from CoSi2 embedded in the silicon substrate. The cavity properties were measured as a function of temperature and power. In films measuring 10 and 25 nm, we find a significant kinetic inductance LK with a non-BCS power-law variation δLK∝T4.3±0.2 at low temperatures. The quality factor of the studied microwave resonances increased almost linearly with thickness, with two-level systems having very little effect. The power dependence of kinetic inductance was analyzed in terms of heat flow due to electron-phonon coupling, which was found stronger than estimated for heat relaxation by regular quasiparticles.
@article{arxiv.2312.14624,
title = {Kinetic inductance in superconducting CoSi$_2$ coplanar microwave transmission lines},
author = {Ekaterina Mukhanova and Weijun Zeng and Elica Anne Heredia and Chun-Wei Wu and Ilari Lilja and Juhn-Jong Lin and Sheng-Shiuan Yeh and Pertti Hakonen},
journal= {arXiv preprint arXiv:2312.14624},
year = {2023}
}