Computational study of electron paramagnetic resonance spectra for Li and Ga vacancies in LiGaO2

A first-principles computational study of the electron paramagnetic resonance (EPR) parameters of Li and Ga vacancies in LiGaO2 is presented. In the EPR active charge states of the neutral lithium vacancy (V-Li(0)) and doubly negative ionized gallium vacancy (V-Ga(2-)), the spin is localized on one of the O neighbors of the vacancy. We compare the calculated EPR parameters for spin density localized on different O neighbors. Good agreement with experiment is obtained for both the g-tensor values and principal axes orientations and the superfhyperfine interaction parameters supporting the prior experimental identification of which O the spin is localized on. The g-tensor orientations are found to be close to the bond rather than the crystalline axes. The high energy of formation of V-Ga compared to V-Li also explains why V-Ga were only observed after high energy irradiation while V-Li were found in as grown samples. On the other hand, the transition levels and Fermi level position explain why V-Li required ionization from the -1 to 0 charge state to become active while V-Ga were already found in the q = -2 EPR active state.