Resonant coherent excitation and energy loss of slow channeling helium ions in AlN

By performing real-time time-dependent density-functional theory dynamic simulations, we report a velocity-dependent charge resonance on slow initial bare ions when channeling through the rocksalt crystalline AlN. Such charge resonance is accompanied by tremendously enhanced stopping at narrow velocity windows, which is attributed to the depletion in electronic screening by bound electrons, when the formation of defect state on projectile is depressed dramatically by the periodical field from lattice arrangement. The enhancement of stopping is not found in simulations with initial neutral incident ion, suggesting the effect of such charge resonance process mainly resides in the charge accumulation during the preequilibrium state, while making marginal influence on the excitation of bound state charge. We also investigated the charge resonance with revised lattice parameter, confirming the periodic atomic arrangement of lattice plane along ion trajectory is the main cause of such charge resonance.