We report the nanoscale spin detection and electron paramagnetic resonance (EPR) spectrum of copper (Cu2+) ions via double electron-electron resonance with single spins in diamond at room temperature and low magnetic fields. We measure unexpectedly narrow EPR resonances with linewidths ∼2−3 MHz from copper-chloride molecules dissolved in poly-lysine. We also observe coherent Rabi oscillations and hyperfine splitting from single Cu2+ ions, which could be used for dynamic nuclear spin polarization and higher sensitivity of spin detection. We interpret and analyze these observations using both spin hamiltonian modeling of the copper-chloride molecules and numerical simulations of the predicted DEER response, and obtain a sensing volume ∼(250nm)3. This work will open the door for copper-labeled EPR measurements under ambient conditions in bio-molecules and nano-materials.
@article{arxiv.2101.02650,
title = {Nanoscale spin detection of copper ions using double electron-electron resonance at room temperature},
author = {Kai Zhang and Shreya Ghosh and Sunil Saxena and M. V. Gurudev Dutt},
journal= {arXiv preprint arXiv:2101.02650},
year = {2022}
}