- https://www.cells.es/ca/actualitat/agenda/esdeveniments-publics-dalba/magnetic-properties-of-amorphous-dyco-thin-film-systems-from-exchange-bias-to-skyrmionic-phases
- Magnetic Properties of amorphous DyCo-thin film systems: from Exchange Bias to Skyrmionic Phases
- 2019-03-29T12:00:00+01:00
- 2019-03-29T13:00:00+01:00
- By Dieter Lott, from Helmholtz-Zentrum Geesthacht
- Què
- events
- Quan
-
Mar 29, 2019
de 12:00 a 13:00 (Europe/Madrid / UTC100) - On
- Sincrotró ALBA, Marie curie meeting room
- Nom de contacte
- Manuel Valvidares
- Telèfon de contacte
- 935924353
- URL de l'esdeveniment
- Lloc web relacionat
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iCal
Keywords: amorphous thin film magnetism, exchange bias, skyrmions, polarized neutron scattering, x-ray magnetic dicroism
Amorphous Rare-Earth - 3d Transition Metal alloys (RE-3d TM) are fascinating magnetic materials due to the easy, straight-forward tunability of their magnetic properties, depending on temperature and the concentration ratio between the RE and 3d TM components. For heavier RE, both sites are antiferromagnetically coupled by an atomic exchange interaction and show a temperature dependent magnetization influenced by the different behaviour of both sites. For Dy(x)Co(100-x) it results into a transition from the Dy to a Co dominant magnetic phase with increasing temperature where the compensation temperature between both sites can be adjusted by the concentration ratio between both sites. Recently, several thin films of Dy(x)Co(x) alloys with varying x were investigated by XMCD and neutron scattering techniques that revealed that the magnetic structure in these films exhibits intriguing non-collinear, complex magnetic configurations [1,2]. As examples, a novel atomic exchange bias effect was found in a thin Dy20Co80 layer of about 50nm with a loop shift by extraordinary 4 Tesla [2] or chirality effects in similar alloys that are coupled to a ferromagnetic layer [3]. Recently, Scanning Transmission X-ray Microscopy (STXM) measurement were carried out using circularly polarized light for magnetic contrast on a thin Dy25Co75 film of 50nm thickness. When the thin film sample is cooled in a small, perpendicular magnetic field it revealed the appearance of bubble domains with an averaged diameter of around 100nm. The evaluation of magnetic bubble pattern observed in the STXM measurements at negative magnetic fields suggest that they are of skyrmionic nature and could be interpreted as the magnetic configurations with a certain winding number. In this talk the fascinating nature of magnetic thin films consisting of amorphous DyCo alloys will be discussed, offering the potential for an alternative concept for future novel magnetic spintronic applications.
References:
[1] K. Chen, D. Lott, F. Radu, F, Choueikani, E. Otero, and P. Ohresser, Phys. Rev. B 91, 024409 (2015)
[2] K. Chen, D. Lott, F. Radu, F. Choueikani, E. Otero, P. Ohresser, Scientific Reports 5, 18377 (2015)
