Ultrafast Demagnetization Dynamics of 4f Antiferromagnets Revealed

Strategic Insights -

Recent research by a team of scientists at the University of Skovde has unveiled the ultrafast demagnetization dynamics of LnRh2Si2 (Ln = Pr, Nd, Sm, Gd, Tb, Dy, Ho) antiferromagnets after excitation by a laser pulse. The study utilized a combination of density functional theory and atomistic spin and spin-lattice dynamics simulations to investigate the microscopic mechanisms behind the observed behaviors. Financial support for this research came from the NWA research programme Research Along Routes by Consortia.

Key Takeaways:

  • The research discovered marked quantitative differences in terms of predicted Curie temperature for most of the systems, especially for those with a large orbital moment of the rare-earth cations.
  • The predicted antiferromagnetic ordering at low temperature was found to be in line with previous experiments, regardless of whether the 4f states of the rare-earth cations were treated as frozen core states or as valence states with added correlation corrections.
  • The demagnetization dynamics simulations demonstrated that despite quite different demagnetization times, magnetization dynamics of all studied LnRh2Si2 antiferromagnets exhibit similar two-step behavior, featuring a fast initial drop followed by slower demagnetization.
  • The demagnetization amplitude was found to depend linearly on laser fluence, especially for low fluences, which is also in agreement with experimental observations.
  • Coupled atomistic spin-lattice dynamics simulations and the heat-conserving three-temperature model confirmed the linear dependence of magnetization on laser fluence.
  • The research team concluded that the microscopic mechanisms behind these behaviors were investigated in detail.

Statistics:

  • The study focused on seven different LnRh2Si2 antiferromagnets, specifically Ln = Pr, Nd, Sm, Gd, Tb, Dy, Ho.
  • The research utilized a combination of density functional theory and atomistic spin and spin-lattice dynamics simulations.
  • The study found a linear dependence of magnetization on laser fluence, especially for low fluences.
  • The predicted antiferromagnetic ordering at low temperature was in line with previous experiments.
  • The demagnetization dynamics simulations demonstrated a two-step behavior for all studied LnRh2Si2 antiferromagnets.

Sources:

  • "Ultrafast Demagnetization Dynamics of 4f Antiferromagnets." Physical Review Materials, vol. 9, no. 9, 2025.
  • Research programme: NWA research programme Research Along Routes by Consortia.
  • Authors: Maryna Pankratova, Vladislav Borisov, Danny Thonig, Rohit Pathak, Olle Eriksson, Anders Bergman, Yoav William Windsor, Laurenz Rettig, and Arthur Ernst.
  • Department of Engineering Sciences, University of Skovde, Sweden.