Multiscale approach to study the creation, pinning, and interaction of skyrmions at transition-metal interfaces

• Applicant: Dr. Bertrand Dupé
• Subject Area: Theoretical Condensed Matter Physics
• Term: from 2015 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 267457786

In this project, we explore the creation, annihilation, and interaction of individual magnetic skyrmions at transition-metal interfaces and their pinning at atomic defects using a multiscale approach. Skyrmions in magnetic materials offer attractive possibilities for future spintronic devices since they are localized, topologically stabilized spin structures which can be manipulated with electric currents of densities that are by orders of magnitudes lower than those required for moving domain walls. One objective is to understand the writing, deleting, and pinning process of skyrmions in an atomic Pd overlayer on Fe/Ir(111) recently reported via spin-polarized scanning tunneling microscopy. In particular, we would like to study atomic defects in or on the Pd overlayer, e.g. Fe or Ir, which have been proposed to act as pinning centers and to facilitate the creation of skyrmions by spin-polarized tunneling currents. Another type of systems considered are transition-metal interfaces or multilayers which are better suited for transport measurements and manipulation at lower magnetic fields. These systems also hold promise for future applications and will be studied experimentally by our collaboration partners. We will design interface systems based on theory such that they can host skyrmions and study in how far the formation of skyrmion phases is influenced by atomic defects in the structure. The pinning of skyrmions at such at atomic defects will also be explored. We will employ a multiscale approach to tackle these issues starting from density functional theory to obtain the strengths of the exchange interaction, the Dzyaloshinskii-Moriya interaction, and the magnetocrystalline anisotropy. The extended Heisenberg model parameterized in this way will be solved numerically using Monte-Carlo simulation and spin dynamics simulations based on the Landau-Lifshitz-Gilbert equations.

• DFG Programme: Research Grants
• International Connection: France
• Co-Investigator: Professor Dr. Stefan Heinze
• Cooperation Partner: Dr. Vincent Cros, Ph.D.