Origin of the enhanced exchange bias in polycrystalline-BiFeO3/Co bilayers by X-ray absorption Spectroscopy
Abstract
Polycrystalline-BiFeO3(BFO)/Co bilayers were grown by pulsed laser deposition (PLD) and magnetron sputtering, with fast laser annealing under magnetic field. The enhanced exchange bias (EB) had been found in the BFO/Co bilayers (Appl. Surf. Sci. 367 (2016) 418). In order to reveal the origin of the enhanced EB in the samples, X-ray absorption Spectroscopy (XAS) of Fe 2p, Co 2p and O 1s were performed. The Co 2p XAS indicated the increase of Co oxidation state and the Fe 2p XAS of sample A and B under laser annealing processes showed that crystal field splitting energy decreased and led to the weakening of spin-orbit coupling with the increasing of the laser fluence. It was considered that the appearance of the oxidation state of Co and Fe2+ ions and the existence of the unidirectional anisotropy due to the laser fluence was responsible for the results and also for the enhanced EB.
- Publication:
-
Journal of Magnetism and Magnetic Materials
- Pub Date:
- April 2018
- DOI:
- 10.1016/j.jmmm.2017.11.105
- Bibcode:
- 2018JMMM..451..734S
- Keywords:
-
- Multiferroic;
- BiFeO<SUB>3</SUB>;
- Exchange bias;
- X-ray absorption Spectroscopy