Theory for the Geometry and Hyperfine Interactions in Neutral Vacancy-Associated Hydrogen (Muonium) Atom Center in Silicon

Hong Li1, N. Sahoo2,3, T.P. Das2, R. Scheuermann1, K. Nagamine1,4

1  Muon Science Laboratory, Institute for Physical and Chemical Research (RIKEN), Wako Shi, Saitama, 351-01, Japan
2  Department of Physics, State University of New York at Albany, Albany, New York, 12222, USA
3  Department of Radiation Oncology, Albany Medical College, Albany, New York, 12208, USA
4  Meson Science Laboratory, High Energy Accelerator Research Organization (KEK), Tsukuba-Shi, Ibaraki, 305, Japan

The electronic structure and associated magnetic hyperfine interactions for the Neutral Vacancy-Associated Hydrogen (Muonium) Atom Center [1,2] in Silicon have been investigated using the Hartree-Fock Cluster Procedure combined with many-body effects incorporated by perturbation methods. The influence of cluster size, size of electronic basis-set and lattice relaxation due to the presence of both the vacancy and muonium atom and vibrational motions of the proton and muon have been studied. The results provide an explanation of the experimentally observed axial anisotropy of the hyperfine interaction tensors and the signs of the isotropic hyperfine constant and dipolar tensor components. The sizes of the calculated hyperfine tensor components are however found to be somewhat larger than experiment. Possible sources that could bridge the remaining differences will be discussed.

[1] B. Bech Nielsen et al., Phys. Rev. Lett. 79, 1507 (1997)
[2] M. Schefzik et al., Solid State Commun. 107, 395 (1998)

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