Ab Initio Spinor Kadanoff-Baym Approach to Nonequilibrium Electron, Phonon and Magnon Dynamics in Itinerant Ferromagnets
Abstract
This work introduces a theoretical framework based on the Kadanoff-Baym equations in spinor space to study ultrafast magnetization dynamics in itinerant ferromagnetic systems from first principles. By incorporating spin-orbit coupling into the ab initio Hamiltonian and generalizing the self-energies to include terms beyond the charge sector, I derive scattering integrals within the Markov approximation and quasiparticle renormalizations for electrons and phonons in the presence of spin-dependent effective interactions within a many-body perturbation theory approach. I explicitly discuss how magnons emerge in this framework, and derive, through suitable approximations, a closed and tractable set of equations for coupled electron, phonon and magnon dynamics that can be solved from first principles. I discuss the equations of motion within a minimal ferromagnetic model, where the coupled equations are solved numerically. This approach allows one to treat coherent and incoherent magnetic dynamics on an equal footing, paving the way for a first principles understanding of ultrafast magnetic dynamics and demagnetization, and opening to a truly predictive theory of femtomagnetism in periodic systems.
Versions
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BibTeX
@misc{marini2026initio,
title = {{Ab Initio Spinor Kadanoff-Baym Approach to Nonequilibrium Electron, Phonon and Magnon Dynamics in Itinerant Ferromagnets}},
author = {Giovanni Marini},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2605.31467},
eprint = {2605.31467},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.31467},
}
RIS
TY - UNPB
TI - Ab Initio Spinor Kadanoff-Baym Approach to Nonequilibrium Electron, Phonon and Magnon Dynamics in Itinerant Ferromagnets
AU - Giovanni Marini
PY - 2026
DA - 2026/09/25
PB - arXiv
DO - 10.48550/arxiv.2605.31467
UR - https://arxiv.org/abs/2605.31467
AB - This work introduces a theoretical framework based on the Kadanoff-Baym equations in spinor space to study ultrafast magnetization dynamics in itinerant ferromagnetic systems from first principles. By incorporating spin-orbit coupling into the ab initio Hamiltonian and generalizing the self-energies to include terms beyond the charge sector, I derive scattering integrals within the Markov approximation and quasiparticle renormalizations for electrons and phonons in the presence of spin-dependent effective interactions within a many-body perturbation theory approach. I explicitly discuss how magnons emerge in this framework, and derive, through suitable approximations, a closed and tractable set of equations for coupled electron, phonon and magnon dynamics that can be solved from first principles. I discuss the equations of motion within a minimal ferromagnetic model, where the coupled equations are solved numerically. This approach allows one to treat coherent and incoherent magnetic dynamics on an equal footing, paving the way for a first principles understanding of ultrafast magnetic dynamics and demagnetization, and opening to a truly predictive theory of femtomagnetism in periodic systems.
ER -