Hyperfine spectroscopy and characterization of muonium in ZnGeP2

Abstract

In this contribution, we report the initial observation of neutral muonium defect centers in ZnGeP2. The spin-precession frequencies in a 4.0 T field yield a zero-temperature hyperfine constant of similar to 1965 MHz for the promptly formed Mu(0) state. Subsequently, we performed T-1(-1) longitudinal depolarization measurements in low magnetic fields. Decoupling curves show a different anisotropic Mu(0) with A(2) = 3185 MHz and D = 374 MHz, where D is the dipolar contribution. The relaxation rates suggest rapid diffusion of Mu(0), most likely via quantum tunneling below 80 K and by thermally activated hops above 100 K. We have determined the ionization energy to be roughly 200 meV. We present our preliminary evaluation of the motion or site transition dynamics in addition to hyperfine characterization of the neutral muonium centers observed in ZnGeP2. (C) 2009 Elsevier B.V. All rights reserved.