Ultrafast spin dynamics in inhomogeneous systems: a density-matrix approach applied to Co/Cu interfaces

Abstract

Ultrafast spin dynamics on femto- to picosecond timescales is simulated within a density-operator approach for a Co/Cu bilayer. The electronic structure is represented in a tight-binding form; during the evolution of the density operator, optical excitation by a femtosecond laser pulse, coupling to a bosonic bath as well as dephasing are taken into account. Our simulations corroborate the importance of interfaces for ultrafast transport phenomena and demagnetisation processes. Moreover, we establish a reflow from Cu $d$ orbitals across the interface into Co $d$ orbitals, which shows up prominently in the mean occupation numbers. On top of this, this refilling manifests itself as a minority-spin current proceeding several layers into the Cu region. The present study suggests that the approach captures essential ultrafast phenomena and provides insight into microscopic processes.

arXiv comment16 pages, 5 figures

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Cited by in corpus (9)

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• Ultrafast magnetization reversal in ferromagnetic spin-valves: an s-d model perspective
• Ultrafast Dynamics of Orbital Angular Momentum of Electrons Induced by Femtosecond Laser Pulses: Generation and Transfer Across Interfaces
• Quantum-classical approach to spin and charge pumping and the ensuing radiation in THz spintronics: Example of ultrafast-light-driven Weyl antiferromagnet Mn${}_3$Sn
• Ultrafast dynamics of electrons excited by femtosecond laser pulses: spin polarization and spin-polarized currents
• Ultrafast spin dynamics: complementing theoretical analyses by quantum-information measures
• Nonlinear spin and orbital Rashba-Edelstein effects induced by a femtosecond laser pulse: Simulations for Au(001)
• Preserving fermionic statistics for single-particle approximations in microscopic quantum master equations
• Adiabatic spin dynamics and effective exchange interactions from constrained tight-binding electronic structure theory: Beyond the Heisenberg regime