Letter pubs.acs.org/NanoLett
Negatively Charged Nitrogen-Vacancy Centers in a 5 nm Thin Diamond Film
12
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K. Ohashi,† T. Rosskopf,‡ H. Watanabe,§ M. Loretz,‡ Y. Tao,‡ R. Hauert,∥ S. Tomizawa,† T. Ishikawa,†,⊥ J. Ishi-Hayase,† S. Shikata,# C. L. Degen,‡ and K. M. Itoh*,† †
School of Fundamental Science and Technology, Keio University, Yokohama 223-8522, Japan Department of Physics, ETH Zurich, Schafmattstrasse 16, 8093 Zurich, Switzerland § Correlated Electronics Group, Electronics and Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 4, 1-1-1, Higashi, Tsukuba, Ibaraki 305-8562, Japan ∥ Nanoscale Material Science, EMPA, Ueberlandstr. 129, 8600 Duebendorf, Switzerland ⊥ Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8904, Japan # Diamond Research Group, Research Institute for Ubiquitous Energy Devices, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31, Midorigaoka, Ikeda, Osaka 563-8577, Japan ‡
ABSTRACT: We report successful introduction of negatively charged nitrogen-vacancy (NV−) centers in a 5 nm thin, isotopically enriched ([12C] = 99.99%) diamond layer by CVD. The present method allows for the formation of NV− in such a thin layer even when the surface is terminated by hydrogen atoms. NV− centers are found to have spin coherence times of between T2 ∼ 10−100 μs at room temperature. Changing the surface termination to oxygen or fluorine leads to a slight increase in the NV− density, but not to any significant change in T2. The minimum detectable magnetic field estimated by this T2 is 3 nT after 100 s of averaging, which would be sufficient for the detection of nuclear magnetic fields exerted by a single proton. We demonstrate the suitability for nanoscale NMR by measuring the fluctuating field from ∼104 proton nuclei placed on top of the 5 nm diamond film.
KEYWORDS: Diamond, nitrogen-vacancy center, chemical vapor deposition, isotope engineering, magnetometry
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detection of a small ensemble of proton nuclear spins in an organic film placed on the surface of a bulk, single-crystal diamond using a single NV− center.17,18 Pushing this scheme to single nuclear spin detection requires formation of stable NV− centers within a distance of
