Hot Electron Enhanced Ion Diffusion in MgO under Ultra-short, Intense Laser Pulses

Electronic excitation of defect states has been proven to reduce the migration barrier which indicates an opportunity to enhance ion diffusion via manipulating the explicit electron distribution. Ultrashort laser pulses have the potential to achieve such manipulation with little physical damage to the material, contrary to other excitation sources, such as proton irradiation. Hence, a detailed understanding of laser-materials interaction is essential for manufacturing with nanoscale precision but still remains unclear, due to its non-linear and non-equilibrium character. Here, we apply real-time TDDFT, which can accurately describe such nonlinear effects, to reveal underlying ultrafast electron dynamics in laser-irradiated MgO. To further understand the influence of excited electrons on the oxygen diffusion, we calculate the time evolution of the occupation number, under different laser frequencies and intensities. Comparison to the distribution of hot electrons following proton irradiation can provide insights into how diffusion enhancement can be achieved by the transient localized electron dynamics and how it depends on specific laser parameters.