Dynamics of optical excitations in a Fe/MgO(001) heterostructure from time-dependent density functional theory

Abstract

In the framework of real-time time-dependent density functional theory (RT-TDDFT) we unravel the layer-resolved dynamics of the electronic structure of a (Fe)${}_1$/(MgO)${}_3$(001) multilayer system after an optical excitation with a frequency below the band gap of bulk MgO. Substantial transient changes to the electronic structure, which persist after the duration of the pulse, are mainly observed for in-plane polarized electric fields, corresponding to a laser pulse arriving perpendicular to the interface. While the strongest charge redistribution takes place in the Fe layer, a time-dependent change in the occupation numbers is visible in all layers, mediated by the presence of interface states. The time evolution of the layer-resolved time-dependent occupation numbers indicates a strong orbital dependence with the depletion from in-plane orbitals (e. g., $d_{x^2-y^2}$ of Fe) and accumulation in out-of-plane orbitals ($d_{3z^2-r^2}$ of Fe and $p_z$ of apical oxygen). We also observe a small net charge transfer away from oxygen towards the Mg sites even for MgO layers which are not directly in contact with the metallic Fe.

arXiv commentAccepted for publication in Physical Review B, https://journals.aps.org/prb/accepted/7507cOe2Nb11e83be6fc09c16cc4051c477ac310e

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Cited by in corpus (6)

• Theoretical description of optical and X-ray absorption spectra of MgO including many-body effects
• Microscopic non-equilibrium energy transfer dynamics in a photoexcited metal/insulator heterostructure
• Spatio-Temporal Electron Propagation Dynamics in Au/Fe/MgO(001) in nonequilibrium: Revealing Single Scattering Events and the Ballistic Limit
• Interface-related magnetic and vibrational properties in Fe/MgO heterostructures from nuclear resonant spectroscopy and first-principles calculations
• Anisotropic carrier dynamics in a laser-excited Fe${}_1$/(MgO)${}_3$(001) heterostructure from real-time time-dependent DFT
• Effect of lattice excitations on transient near edge X-ray absorption spectroscopy