Electron-nuclear double resonance study of ions in crystals

• Published in: Solid state communications 2009-11, Vol.149 (41-42), p.1818-1821
• Main Authors: Bunton, P.H., Baker, D.B., Engquist, D.E., Klemm, M., Horn, S., Yang, Shan, Evans, S.M., Halliburton, L.E.
• Format: Article
• Language: English
• ISSN: 0038-1098
• DOI: 10.1016/j.ssc.2009.07.012

Electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) are used to identify and characterize V (4+) ions in a bulk single crystal of vanadium dioxide (V O(2)). These S=1/2 defects are observed in the as-grown crystal because an adjacent nonmagnetic M(4+) impurity, e.g., a Si(4+) ion, has destroyed the normal antiferromagnetic coupling associated with the close pairs of V (4+) ions that occur in the low-temperature monoclinic phase of V O(2). EPR spectra taken near 5 K with the magnetic field along the [110] and [001] axes show resolved hyperfine patterns due to one (51)V nucleus. ENDOR spectra taken at 5 K with the magnetic field parallel to the [001] axis have large nuclear electric quadrupole splittings as a result of a significant electric field gradient at the (51)V nucleus. Spin-Hamiltonian parameters describing the electron Zeeman, hyperfine, and nuclear electric quadrupole interactions are reported.