Ultrafast magnetic moment transfer and bandgap renormalization in monolayer FeCl${}_2$

Abstract

The microscopic origin of laser-induced ultrafast demagnetization remains an open question, to which the non-thermal electronic distribution plays a vital role at the initial stage. Herein, we investigate the connection between the non-thermal electronic distribution and the ultrafast spin dynamics as well as the electronic structure evolution in ferromagnetic FeCl${}_2$ monolayer using real-time time-dependent density functional theory (rt-TDDFT) with self-consistent Hubbard $U$ correction. Our simulations reveal that femtosecond laser pulses induce ultrafast magnetic moment transfer from Fe to Cl atoms. More importantly, through a comprehensive analysis of orbital-resolved electronic structure, we elucidate the microscopic origin of this transfer, attributing it to specific intra-atomic and inter-atomic charge transfer pathways driven by non-thermal excitations. The extent of demagnetization of Fe atoms exhibits a non-monotonic dependence on the laser photon energy, reaching a maximum at the resonant excitation. In addition, the dynamical evolution of the band structure was studied based on the eigenstates of the instantaneous Hamiltonian. Under resonant excitation, the bandgap reduction reaches up to $41\%$ within tens of fs. These findings provide fundamental insights into ultrafast spin control and suggest a strategy to optically engineer the magnetism in two-dimensional magnetic materials.

arXiv comment8 pages, 8 figures

References in corpus (17)

• Relativistic separable dual-space Gaussian Pseudopotentials from H to Rn
• Super-Diffusive Spin-Transport as a Mechanism of Ultrafast Demagnetization
• Antiferromagnetic opto-spintronics: Part of a collection of reviews on antiferromagnetic spintronics
• Real-space grids and the Octopus code as tools for the development of new simulation approaches for electronic systems
• Octopus, a computational framework for exploring light-driven phenomena and quantum dynamics in extended and finite systems
• Polarized phonons carry the missing angular momentum in femtosecond demagnetization
• Ultrafast modification of Hubbard $U$ in a strongly correlated material: ab initio high-harmonic generation in NiO
• Ab initio investigation of Elliott-Yafet electron-phonon mechanism in laser-induced ultrafast demagnetization
• Laser-Driven Multiferroics and Ultrafast Spin Current Generation
• Ab initio theory of electron-phonon mediated ultrafast spin relaxation of laser-excited hot electrons in transition-metal ferromagnets
• Self-consistent DFT+U method for real-space time-dependent density functional theory calculations
• Terahertz field-induced metastable magnetization near criticality in FePS3
• All-optical nonequilibrium pathway to stabilizing magnetic Weyl semimetals in pyrochlore iridates
• Probing spin dynamics of ultra-thin van der Waals magnets via photon-magnon coupling
• Where does the spin angular momentum go in laser induced demagnetisation?
• Unique electronic state in ferromagnetic semiconductor FeCl${}_2$ monolayer
• Ultrafast Spin Dynamics and Photoinduced Insulator-to-Metal Transition in $\alpha$-$RuC{l}_3$