Pulsed electron spin resonance of an organic microcrystal by dispersive readout

Ailsa K V Keyser; Jonathan J Burnett; Sergey E Kubatkin; Andrey V Danilov; Mark Oxborrow; Sebastian E de Graaf; Tobias Lindström

doi:10.1016/j.jmr.2020.106853

Pulsed electron spin resonance of an organic microcrystal by dispersive readout

J Magn Reson. 2020 Dec:321:106853. doi: 10.1016/j.jmr.2020.106853. Epub 2020 Oct 20.

Authors

Ailsa K V Keyser¹, Jonathan J Burnett², Sergey E Kubatkin³, Andrey V Danilov³, Mark Oxborrow⁴, Sebastian E de Graaf², Tobias Lindström²

Affiliations

¹ National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UK; Imperial College London, Exhibition Road, SW7 2AZ, UK. Electronic address: akk916@ic.ac.uk.
² National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UK.
³ Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, SE-41296 Gothenburg, Sweden.
⁴ Imperial College London, Exhibition Road, SW7 2AZ, UK.

PMID: 33128916
DOI: 10.1016/j.jmr.2020.106853

Abstract

We establish a testbed system for the development of high-sensitivity Electron Spin Resonance (ESR) techniques for small samples at cryogenic temperatures. Our system consists of a NbN thin-film planar superconducting microresonator designed to have a concentrated mode volume to couple to a small amount of paramagnetic material, and to be resilient to magnetic fields of up to 400mT. At 65mK we measure high-cooperativity coupling (C≈19) to an organic radical microcrystal containing 10¹² spins in a pico-litre volume. We detect the spin-lattice decoherence rate via the dispersive frequency shift of the resonator. Techniques such as these could be suitable for applications in quantum information as well as for pulsed ESR interrogation of very few spins to provide insights into the surface chemistry of, for example, the material defects in superconducting quantum processors.

Keywords: Dispersive readout; High sensitivity ESR for small volumes; Superconducting resonators.