On Thursday, the 07th Of December 2017 at 14h00, Chloé BOUARD from DRF/INAC/SPINTEC, will defend her PhD thesis entitled “Elaboration and characterization of magnetic systems for skyrmion observations”
Place : Amphitheater from CNRS building A-3rd floor – 25 rue des Martyrs, Grenoble
New technology needs huge storage capacity together with high speed and low-cost transport of information. Current devices meeting their limits, research on new solutions of storage is needed.
One of them, proposed a few years ago, consists in using magnetic domain walls. Aligning them in nanowires and using the thickness of the layers could allow the realization of a tridimensional recording device and then improve the storage capacity.
A new object more robust and less sensitive to perturbations has been discovered since. Skyrmion is now widely studied. It has been experimentally observed in two kinds of systems. The first one is helimagnet, with non centrosymmetric crystal structure. FeGe is one of them, with the highest critical temperature observed yet. Skyrmion has been observed as well at the interface between a heavy metal with strong spin-orbit coupling and a ferromagnet. In particular, multilayers with non-symmetric interfaces are very promising systems for manipulation of skyrmions at room temperature.
Nevertheless, the elaboration of systems for industrial devices and reliable detection of skyrmions is still tricky nowadays. These two problematics are explored in this thesis, applied to two different systems. A protocol to grow helimagnetic FeGe thin films was first established, thanks to structural characterization mainly based on X-ray diffraction. Growth of multilayers with non symmetrical interfaces [heavy metal 1/ferromagnet/heavy metal 2]n was studied as well. These systems were then magnetically characterized, using numerous techniques such as magnetic imaging, magneto transport measurements and magnetic spectroscopy.