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We investigate the low-field relaxation of nuclear hyperpolarization in undoped and highly doped silicon microparticles at room temperature following removal from high field. For nominally undoped particles, two relaxation time scales are identified for ambient fields above 0.2 mT. The slower, T_1s, is roughly independent of ambient field; the faster, T_1f, decreases with increasing ambient field. A model in which nuclear spin relaxation occurs at the particle surface via a two-electron mechanism is shown to be in good agreement with the experimental data, particularly the field-independence of T_1s. For boron-doped particles, a single relaxation time scale is observed. This suggests that for doped particles, mobile carriers and bulk ionized acceptor sites, rather than paramagnetic surface states, are the dominant relaxation mechanisms. Relaxation times for the undoped particles are not affected by tumbling in a liquid solution.
Direct dynamic nuclear polarization of 1H nuclei in frozen water and water-ethanol mixtures is demonstrated using silicon nanoparticles as the polarizing agent. Electron spins at dangling-bond sites near the silicon surface are identified as the sour
In this work, we devise a fast and effective nuclear spin hyperpolarization scheme, which is in principle magnetic field and temperature independent. We use this scheme to experimentally demonstrate polarizations of up to 66% for phosphorus donor nuc
Nuclear polarization dynamics are measured in the nuclear spin bi-stability regime in a single optically pumped InGaAs/GaAs quantum dot. The controlling role of nuclear spin diffusion from the dot into the surrounding material is revealed in pump-pro
Colour centres with long-lived spins are established platforms for quantum sensing and quantum information applications. Colour centres exist in different charge states, each of them with distinct optical and spin properties. Application to quantum t
We discuss the fine structure and spin dynamics of spin-3/2 centers associated with silicon vacancies in silicon carbide. The centers have optically addressable spin states which makes them highly promising for quantum technologies. The fine structur