On-chip superconducting resonator devices for sensitive spin detection at high magnetic fields.*

The ability to probe spin-photon interactions using Electron Spin Resonance techniques has gained significant interest given the realization of hybridized states between microwave photons and different spin ensembles.^1-3 On-chip superconducting resonators provides a way to inductively couple a spin two level system with a resonant electromagnetic mode leading to enhanced sensitivity⁴ when compared to traditional 3D resonators. We demonstrate the implementation of λ/4 resonator placed after a coplanar waveguide-to-stripline transition on a 20 nm thick Nb film. Temperature effects on the losses and resonance frequency are studied for bare and spin loaded resonators. A resonance signal at 0.62 T for a spin S=1/2 system is presented, demonstrating the feasibility of such on-chip structures for high magnetic field electron spin detection.

¹I. Chiorescu et al., Phys. Rev. B 82, 024413 (2010).
²D. I. Schuster et al., Phys. Rev. Lett. 105, 140501 (2010).
³Y. Kubo et al., Phys. Rev. Lett. 105, 140502 (2010).
⁴S. Probst et al., App. Phys. Lett. 111, 202604 (2017).