PGI-1 Talk: Marius Weber

Quantum Theory of Materials Seminar

https://iffvc.fz-juelich.de/rooms/nat-ham-1kc-oip

Ultrafast electron dynamics in magnetic systems

Systems with antiferromagnetic ordering in real space often exhibit topological features in momentum space, which have only recently been investigated in a comprehensive fashion [1]. For example, depending on the magnetic order, they can exhibit band structures with a pronounced anisotropy in the band dispersion and in the spin structure of their singleparticle states due to Dirac cones. We present numerical calculations of the electron dynamics due to electron-phonon interactions [2,3] in model systems with two-dimensional k-space that capture key properties of antiferromagnetic Dirac materials in momentum space. In addition, the newly proposed altermagnetic materials [4] exhibit several intriguing properties, including a distinctive anisotropic band-structure landscape with an alternating spin arrangement. We calculate the electronic dynamics in altermagnetic KRu4O8. The abinitio band structure and corresponding dipole matrix elements are used as input to determine optically excited carrier distributions from a Fermi's Golden Rule [5] approach. In order to investigate the characteristics of electronic dynamics in these systems, it is crucial to compute the microscopic momentum-dependent scattering dynamics throughout the whole Brillouin zone. We utilize a tight-binding model with a two-dimensional k-space and optimize the model parameters according to the DFT band structure in order to capture the essential momentum-space characteristics of KRu4O8. Using an efficient implementation of electronic scattering processes that fulfils important conservation laws, we numerically determine the electron dynamics resulting from electron-phonon [2] and electron-electron scattering processes. We characterize the influence on charge and spin dynamics throughout the entire Brillouin zone and highlight the importance of Elliot-Yafet spin flips.

[1] L. Šmejkal et al.; Phys. Rev. Let 118, 106402 (2017)
[2] K. Leckron et al.; Phys. Rev. B 96, 140408 (2017).
[3] M. Weber et. al.; arXiv:2305.00775
[4] L. Šmejkal et al.; Phys. Rev. X 12, 031042 (2022)
[4] S. Essert et al., Phys. Rev. B 84, 224405 (2011).

Contact

Prof. Dr. Stefan Blügel
Phone: +49 2461 61-4249
Email: s.bluegel@fz-juelich.de

Marius Weber
Department of Physics and Research Center OPTIMAS, University of Kaiserslautern-Landau
Email: Mweber@rhrk.uni-kl.de