spin coherence

waveguide
Fig-C-scaled_f34_nofit_sm
The figure at left shows an ODMR signal produced by scanning a magnetic tip at a range of heights above the diamond surface. The dark region indicates reduced photon count from the single NV when the tip field brings the spin into resonance with an applied microwave field of fixed frequency. From such measurements we can extract relative depths between NV centers in the nitrogen doped diamond.
Diamond Growth and Spin Coherence
We use chemical vapor deposition (CVD) at UCSB to grow high quality single-crystal diamond films for nitrogen-vacancy (NV) center magnetometry and related projects involving NV centers. In the CVD process we have incorporated process steps where the diamond is doped with nitrogen gas to gently create a few nanometer-thick diamond layer where NV centers can be formed. Having NVs within nanometers of the diamond surface is critical if they are to be used to sense weak magnetic fields from systems external to the diamond, such as single electronic and nuclear spins, because the spin-spin coupling falls off rapidly with distance.

We are using a homebuilt confocal microscope combined with a magnetic force microscope (MFM) probe to both address the NV spin and employ a scanning magnetic field gradient for sub-diffraction limited determination of the depth of NVs. Our goal is to understand how the spin coherence properties depend on surface effects such as strain and coupling to paramagnetic impurities and thus how to optimize these shallow “doped NV” magnetic field sensors.


Publications

Double-Quantum Spin-Relaxation Limits to Coherence
of Near-Surface Nitrogen-Vacancy Centers – Phys. Rev. Lett. 118, 197201 (2017)
Hyperfine-enhanced gyromagnetic ratio of a nuclear spin in diamond – New Journal of Physics 18, 083016 (2016)
Double-quantum spin-relaxation limits to coherence of near-surface nitrogen-vacancy centers – arXiv:1607.02553 (2016)
Patterned Formation of Highly Coherent Nitrogen-Vacancy Centers Using a Focused Electron Irradiation Technique – Nano Lett. ASAP (2016)
Probing surface noise with depth-calibrated spins in diamond – Phys. Rev. Lett., 113, 027602 (2014)
Three-dimensional localization of spins in diamond using 12C implantation – Appl. Phys. Lett. 105, 052406 (2014)
Engineering shallow spins in diamond with nitrogen delta-doping – Appl. Phys. Lett. 101, 082413 (2012)