Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7111527 | Diamond and Related Materials | 2013 | 4 Pages |
Abstract
Thermal neutron irradiation of synthetic type Ib diamond, followed by annealing, results in a number of paramagnetic point defect centers. One of these is the composite defect designated W29. Previous EPR measurements have shown that the W29 center (SÂ =Â 3/2) is a charged divacancy [VV]â with spin Hamiltonian parameters similar to those of the R4/W6 neutral divacancy center [VV]0 (SÂ =Â 1) found in irradiated high purity type IIa diamond. The present EPR linewidth and spin-lattice relaxation rate measurements, made as a function of temperature on the W29 center, show that an Orbach two-phonon process, with a gap of ~Â 20Â meV, plays a dominant role in determining the relaxation behavior above 20Â K. Below 20Â K a direct single phonon process provides the spin-lattice relaxation mechanism and the relaxation times become long, of the order of milliseconds. The linewidth behavior with temperature is accounted for in terms of changes in the spin dynamics.
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Authors
J.K. Kirui, J.A. van Wyk, M.J.R. Hoch,