Ultrafast demagnetization in bulk versus thin films: An ab initio study

K. Krieger, P. Elliott, T. Müller, N. Singh, J. K. Dewhurst, E. K.U. Gross, S. Sharma*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

44 Scopus citations

Abstract

We report ab initio simulations of the quantum dynamics of electronic charge and spins when subjected to intense laser pulses. By performing these purely electron-dynamics calculations for a thin film and for the bulk of Ni, we conclude that formation of surfaces has a dramatic influence of amplifying the laser induced demagnetization. The reason for this amplification is enhanced spin-currents on the surface of the thin films. We show that the underlying physics of demagnetization for bulk is dominated by spin-flips induced by spin-orbit coupling. In the case of thin films, the dominant cause of demagnetization is a combination of the flow of spin-currents and spin-flips. Furthermore, a comparison of our results with experimental data shows that below ∼120 fs processes of demagnetization are entirely dominated by purely electronic processes followed by which dissipative effects like the Elliott-Yafet mechanism start to contribute significantly.

Original languageAmerican English
Article number224001
JournalJournal of Physics Condensed Matter
Volume29
Issue number22
DOIs
StatePublished - 25 Apr 2017
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2017 IOP Publishing Ltd.

Keywords

  • TDDFT
  • ab initio study
  • spin dynamics
  • ultrafast demagnetization

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