Skyrmions and antidamping in ultra thin films of Heusler alloy Co₂FeAl and NiFe sandwiched in multilayers

The magnetic switching is an important property of a ferromagnetic (FM) substance such as Fe single crystal, Heusler alloy thin films, etc. Two important discoveries, namely the formation of complex magnetic field configuration, namely the Skyrmions and the phenomenon of Spin Transfer Torque (STT), are both critical to the degree of ease/ difficulty in switching of the magnetization M of a FM thin film. While the former is being investigated with regards to the static DC field response, the latter is associated with the dynamic field response in multilayered thin films. The Skyrmions are small swirling field like vortex structures (size ∼50 nm) in material systems with broken inversion symmetry. Topologically stable, the Skyrmions can be easily moved/switched, created and annihilated. These make them potentially suitable for data storage and logic technologies. However, the stabilization of Skyrmions is mostly reported in patterned magnetic structures and in most cases reported at low temperatures until recently. We would present and discuss the existence of Skyrmions at room temperatures in un-patterned Si/Ta/Co₂FeAl/MgO trilayers as confirmed directly from the magnetic force microscopy. These trilayers are fabricated by employing ion-beam sputtering