Chiral magnetic structures in thin films and finite nanoparticles
Prof. Laszlo Szunyogh (Department of Theoretical Physics, Budapest University, University of Konstanz)

Thin magnetic films and nanoparticles deposited on different substrates exhibit a rich variety of magnetic structures the knowledge of which is inevitably important for potential technological applications. Our theoretical approach is based on a fully relativistic implementation of the density functional theory in the local spin-density approximation. The magnetic ground state of the system is determined either by means of ab initio spin-dynamics relying on the so-called constrained density functional theory or by mapping the first principles total energy onto a Heisenberg like Hamiltonian to be treated via standard methods of statistical physics such as Monte Carlo simulations or real-time spin-dynamics simulations.
The relativistic treatment of the electronic structure allows for a full account of the magnetic anisotropy and of the anisotropic exchange interactions and of the Dzyaloshinskii-Moriya interactions (DMI). Several novel and challenging consequences of the Dzyaloshinsky-Moriya interaction (DMI) have been revealed, such as the chirality of domain walls [1], the non-reciprocity of spin waves [2], the formation of spin-spiral [3] and skyrmion states [4] in ultrathin films. A vast amount of research effort has been concentrated on tuning the balance between interactions preferring collinear and non-collinear ordering by the appropriate choice of magnetic materials and heavy metals with high spin-orbit coupling [5,6,7].