Magnetization reversal process in a perpendicular synthetic ferrimagnet
  O.V. Koplak1,2, A. Talantsev1,2, A. Bezverhnii1, R. Morgunov1,2, S. Mangin3
1Institute of Problems of Chemical Physics, 142432, Chernogolovka, Russia
2Tambov State Technical University, 392000, Tambov, Russia
3Institut Jean Lamour, UMR 7198 CNRS, Université de Lorraine, France
E-mail: o.koplak@gmail.com

Engineering of new spintronic devices used in magnetic memory and data storage devices requires synthetic antiferromagnets  with perpendicular anisotropy. Two types of magnetization of synthetic antiferromagnet bilayer systems with strong perpendicular anisotropy namely CoFeB/Ta/CoFeB and Pt/Co/Ir/Co/Pt have been studied. Energy diagrams and simulation of real hysteresis loops for antiferromagnetically coupled bilayer are shown on the Fig.1. Top panels: solid lines indicate energy curves E(H) for stable magnetic states ↑↑ – green, ↑↓ – violet, ↓↑ – orange, and ↓↓ – blue curve; dashed lines are curves for the same states shifted upwards by the anisotropy barrier. Dot lines indicate the correspondence between the critical points on the energy diagrams and transition fields on the hysteresis loops. Single reversal (magnetization reversal of single layer) corresponding to transitions between parallel (P) and antiparallel (AP) alignments of the magnetizations in the top and bottom layers and double reversal (magnetizations reversals of both ferromagnetic layers) corresponding to the transitions between the two antiparallel alignment. 
Figure 1. Energy diagrams (top panels) and simulation (bottom panels) of real hysteresis loops for antiferromagnetically coupled bilayer.
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1 O. Koplak, et al, J. Magn. Magn. Mat. 433, 91 (2017).
2 A. Talantsev, O. Koplak, R. Morgunov. Superlattices and Microstructures 95, 14 (2016).