Browsing by Author "Vlasov, Sergei M."

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  • Duplication, Collapse, and Escape of Magnetic Skyrmions Revealed Using a Systematic Saddle Point Search Method
    (2018-11-06) Müller, Gideon P.; Bessarab, Pavel F.; Vlasov, Sergei M.; Lux, Fabian; Kiselev, Nikolai S.; Blügel, Stefan; Uzdin, Valery M.; Jónsson, Hannes
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Various transitions that a magnetic Skyrmion can undergo are found in calculations using a method for climbing up the energy surface and converging onto first order saddle points. In addition to collapse and escape through a boundary, the method identifies a transition where the Skyrmion divides and forms two Skyrmions. The activation energy for this duplication process can be similar to that of collapse and escape. A tilting of the external magnetic field for a certain time interval is found to induce the duplication process in a dynamical simulation. Such a process could turn out to be an important avenue for the creation of Skyrmions in future magnetic devices.
  • Magnetic skyrmion annihilation by quantum mechanical tunneling
    (2020-08) Vlasov, Sergei M.; Bessarab, Pavel F.; Lobanov, Igor S.; Potkina, Mariia N.; Uzdin, Valery M.; Jonsson, Hannes
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Magnetic skyrmions are nano-scale magnetic states that could be used in various spintronics devices. A central issue is the mechanism and rate of various possible annihilation processes and the lifetime of metastable skyrmions. While most studies have focused on classical over-the-barrier mechanism for annihilation, it is also possible that quantum mechanical tunneling through the energy barrier takes place. Calculations of the lifetime of magnetic skyrmions in a two-dimensional lattice are presented and the rate of tunneling compared with the classical annihilation rate. A remarkably strong variation in the onset temperature for tunneling and the lifetime of the skyrmion is found as a function of the values of parameters in the extended Heisenberg Hamiltonian, i.e. the out-of-plane anisotropy, Dzyaloshinskii-Moriya interaction and applied magnetic field. Materials parameters and conditions are identified where the onset of tunneling could be observed on a laboratory time scale. In particular, it is predicted that skyrmion tunneling could be observed in the PdFe/Ir(111) system when an external magnetic field on the order of 6Tis applied.