Perpendicular magnetic anisotropy in ultrathin CoFeB layers
Investigation of magnetic anisotropy in ultra-thin magnetic films
Ultra-thin films (~nm) have recently been integrated into state-of-the-art magnetic tunnel junctions in order to realise spin-transfer-torque driven magnetic random access memories (MRAM). These films possess perpendicular anisotropy due to their high surface to volume ratio and induced magnetic anisotropy in the presence of adjacent layers.
In contrast to the usual rare-earth based multilayers (e.g. Co/Pt, Co/Pd), MgO and other oxides have been shown to induce perpendicular magnetic anisotropy in thin films. Both the understanding and control of such films is crucial for their exploitation in spin-transfer driven devices.
As an example project, the complimentary techniques of extraordinary Hall effect, spin-torque ferromagnetic resonance, standard ferromagnetic resonance as well as standard magnetometry can be used to determine the magnetic properties of both extended films and free standing "nano-pillar" structures. The critical aspect of high temperature annealing and its time dependence can also be investigated in the context of a bachelor or masters project. Students would be in charge of thin-film investigation, annealing and analysis. If so required sample fabrication can also be performed.