Multiple Magnetoionic Regimes in Ta/Co20Fe60B20/ HfO2

R. Pachat (1) , D. Ourdani (2) , J. W. van Der Jagt (1) , M.-A. Syskaki , A. Di Pietro (3) , Y. Roussigné (2) , S. Ono (4) , M. S. Gabor (5) , M. Chérif (2) , G. Durin (3) , J. Langer , M. Belmeguenai (2) , D. Ravelosona (1) , L Herrera Diez (1)

1 C2N - Centre de Nanosciences et de Nanotechnologies
2 LSPM - Laboratoire des Sciences des Procédés et des Matériaux
3 INRiM - Istituto Nazionale di Ricerca Metrologica
4 Central Research Institute of Electrical Power Industry
5 Technical University of Cluj-Napoca

In Ta/CoFeB/HfO2 stacks a gate voltage drives, in a nonvolatile way, the system from an underoxidized state exhibiting in-plane anisotropy (IPA) to an optimum oxidation level resulting in perpendicular anisotropy (PMA) and further into an overoxidized state with IPA. The IPA → PMA regime is found to be significantly faster than the PMA → IPA regime, while only the latter shows full reversibility under the same gate voltages. The effective damping parameter also shows a marked dependence with gate voltage in the IPA → PMA regime, going from 0.029 to 0.012, and only a modest increase to 0.014 in the PMA → IPA regime. The existence of two magneto-ionic regimes has been linked to a difference in the chemical environment of the anchoring points of oxygen species added to underoxidized or overoxidized layers. Our results show that multiple magneto-ionic regimes can exist in a single device and that their characterization is of great importance for the design of high performance spintronics devices.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

R. Pachat, D. Ourdani, J. W. van Der Jagt, M.-A. Syskaki, A. Di Pietro, et al.. Multiple Magnetoionic Regimes in Ta/Co20Fe60B20/ HfO2. Physical Review Applied, 2021, 15 (6), pp.064055. ⟨10.1103/PhysRevApplied.15.064055⟩. ⟨hal-03310930⟩