Scalable microresonators for room-temperature detection of electron spin resonance from dilute, sub-nanoliter volume solids

Toroidal metamaterials make tiny, better-ringing bells for microwaves. We report a microresonator platform that allows room temperature detection of electron spins in volumes on the order of 100 pl, and demonstrate its utility to study low levels of dopants in perovskite oxides. We exploit the toroi...

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Bibliographic Details
Published in:Science advances 2020-10, Vol.6 (44)
Main Authors: Abhyankar, Nandita, Agrawal, Amit, Shrestha, Pragya, Maier, Russell, McMichael, Robert D., Campbell, Jason, Szalai, Veronika
Format: Article
Language:English
Subjects:
Materials Science
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Summary:Toroidal metamaterials make tiny, better-ringing bells for microwaves. We report a microresonator platform that allows room temperature detection of electron spins in volumes on the order of 100 pl, and demonstrate its utility to study low levels of dopants in perovskite oxides. We exploit the toroidal moment in a planar anapole, using a single unit of an anapole metamaterial architecture to produce a microwave resonance exhibiting a spatially confined magnetic field hotspot and simultaneously high quality-factor ( Q -factor). To demonstrate the broad implementability of this design and its scalability to higher frequencies, we deploy the microresonators in a commercial electron paramagnetic resonance (EPR) spectrometer operating at 10 GHz and a NIST-built EPR spectrometer operating at 35 GHz. We report continuous-wave (CW) EPR spectra for various samples, including a dilute Mn 2+ -doped perovskite oxide, CaTiO 3 , and a transition metal complex, CuCl 2 .2H 2 O. The anapole microresonator presented here is expected to enable multifrequency EPR characterization of dopants and defects in perovskite oxide microcrystals and other volume-limited materials of technological importance.
ISSN:2375-2548
2375-2548
DOI:10.1126/sciadv.abb0620