English abstract
The investigation of magnetic skyrmions in thin film multilayers holds
promise for enhancing spintronic technologies due to their stability and
potential for low-power applications. This thesis explores the magnetic
properties and behaviors of Pt/Co/Ta and Pt/Co/W asymmetric multilayers,
focusing on the effect of different heavy metals and the interfacial
Dzyaloshinskii-Moriya interaction (IDMI) on the formation and the stability of
skyrmions. The study employs consistent layer thicknesses and repetitions to
specifically analyze the impact of the heavy metal layers.
The Pt/Co/W multilayer exhibits perpendicular magnetic anisotropy
(PMA) with a saturation field of 800 Oe. Initially, a maze-like domain structure
is present at zero field, which transitions into a lower-density labyrinth
structure at 250 Oe, accompanied by isolated skyrmions. Increasing the
magnetic field to 500 Oe leads to the formation of short, straight wire-like
structures along with magnetic skyrmions. Further increasing the field to 600
Oe results in a higher density of skyrmions, with the disappearance of domain
structures.
Conversely, the Pt/Co/Ta multilayer shows partial PMA with a saturation
field of 700 Oe. Labyrinth domains are observed at zero field, with a
combination of thin maze-like domains and low-density skyrmions appearing
at 200 Oe. At higher fields nearing the saturation point, skyrmions and other
topological structures are observed.
These results underscore the significant role of the choice of heavy metal
and IDMI in shaping the magnetic characteristics and skyrmion behavior
in these multilayers. The insights gained from this study contribute to the
development and optimization of magnetic thin films for advanced spintronic
devices.
