title: Approach to dark spin cooling in a diamond nanocrystal.
abstract: Using a Hartman-Hahn protocol, we demonstrate spin polarization transfer from a single, optically polarized nitrogen-vacancy (NV) center to the ensemble of paramagnetic defects hosted by an individual diamond nanocrystal. Owing to the strong NV-bath coupling, the transfer takes place on a short, microsecond time scale. Upon fast repetition of the pulse sequence, we observe strong polarization transfer blockade, which we interpret as an indication of spin bath cooling. Numerical simulations indicate that the spin bath polarization is nonuniform throughout the nanoparticle, averaging approximately 5% over the crystal volume, but reaching up to 25% in the immediate vicinity of the NV. These observations may prove relevant to the planning of future bath-assisted magnetometry tests.
authors.affiliation: Department of Physics, CUNY-City College of New York, New York, New York 10031, United States.
authors.forename: Abdelghani
authors.initials: A
authors.lastname: Laraoui
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Meriles
mesh_terms: D003198:Computer Simulation; D003460:Crystallization / Q000379:methods*; D018130:Diamond / Q000737:chemistry*; D060526:Magnetic Fields; D008422:Materials Testing; D008956:Models, Chemical; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D013113:Spin Labels; D013499:Surface Properties
chemical_list: D013113:Spin Labels; D018130:Diamond