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Title: Dynamic nuclear polarization of {sup 29}Si nuclei in isotopically controlled phosphorus doped silicon

Dynamic nuclear polarization (DNP) of {sup 29}Si nuclei in isotopically controlled silicon single crystals with the {sup 29}Si isotope abundance f{sub 29Si} varied from 1.2% to 99.2% is reported. It was found that both the DNP enhancement and {sup 29}Si nuclear spin-lattice relaxation time under saturation of the electron paramagnetic resonance transitions of phosphorus donors increase with the decrease in the {sup 29}Si abundance. A remarkably large steady-state DNP enhancement, E{sup ss}=2680 which is comparable to the theoretical upper limit of 3310, has been achieved through the ''resolved'' solid effect that has been identified clearly in the f{sub 29Si}=1.2% sample. The DNP enhancement depends not only on the {sup 29}Si abundance but also on the electron spin-lattice relaxation time that can be controlled by temperature and/or illumination. The linewidth of {sup 29}Si NMR spectra after DNP shows a linear dependence on f{sub 29Si} for f{sub 29Si}{<=}10% and changes to a square-root dependence for f{sub 29Si}{>=}50%. Comparison of experimentally determined nuclear polarization time with nuclear spin diffusion coefficients indicates that the rate of DNP is limited by the polarization transfer rather than by spin diffusion.
Authors:
; ; ; ;  [1] ;  [2]
  1. School of Fundamental Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan)
  2. (Russian Federation)
Publication Date:
OSTI Identifier:
21287045
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. B, Condensed Matter and Materials Physics; Journal Volume: 80; Journal Issue: 4; Other Information: DOI: 10.1103/PhysRevB.80.045201; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; COMPARATIVE EVALUATIONS; DIFFUSION; DINITROPHENOL; DOPED MATERIALS; ELECTRON SPIN RESONANCE; ELECTRONS; ILLUMINANCE; MONOCRYSTALS; NMR SPECTRA; NUCLEAR MAGNETIC RESONANCE; PARAMAGNETISM; PHOSPHORUS ADDITIONS; POLARIZATION; SATURATION; SILICON; SILICON 29; SOLIDS; SPIN; SPIN-LATTICE RELAXATION; STEADY-STATE CONDITIONS