Investigation of surface magnetic noise by shallow spins in diamond.
We present measurements of spin relaxation times (T1, T1ρ, T2) on very shallow (≲5  nm) nitrogen-vacancy centers in high-purity diamond single crystals. We find a reduction of spin relaxation times up to 30 times compared to bulk values, indicating the presence of ubiquitous magnetic impurities associated with the surface. Our measurements yield a density of 0.01-0.1μB/nm2 and a characteristic correlation time of 0.28(3) ns of surface states, with little variation between samples and chemical surface terminations. A low temperature measurement further confirms that fluctuations are thermally activated. The data support the atomistic picture where impurities are associated with the top carbon layers, and not with terminating surface atoms or adsorbate molecules. The low spin density implies that the presence of a single surface impurity is sufficient to cause spin relaxation of a shallow nitrogen-vacancy center.
Department of Physics, ETH Zurich, Otto Stern Weg 1, 8093 Zurich, Switzerland.
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Rosskopf
Department of Physics, ETH Zurich, Otto Stern Weg 1, 8093 Zurich, Switzerland.
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Dussaux
School of Fundamental Science and Technology, Keio University, Yokohama 223-8522, Japan.
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Ohashi
Department of Physics, ETH Zurich, Otto Stern Weg 1, 8093 Zurich, Switzerland.
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Loretz
Department of Physics, ETH Zurich, Otto Stern Weg 1, 8093 Zurich, Switzerland.
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Schirhagl
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.
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Watanabe
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.
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Shikata
School of Fundamental Science and Technology, Keio University, Yokohama 223-8522, Japan.
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Itoh
Department of Physics, ETH Zurich, Otto Stern Weg 1, 8093 Zurich, Switzerland.
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