Magneto‐ionics in annealed W/CoFeB/HfO2 thin films

Rohit Pachat (1) , Djoudi Ourdani (2) , Maria‐andromachi Syskaki (3) , Alessio Lamperti (4) , Subhajit Roy (1) , Song Chen (5) , Adriano Di Pietro (6, 7) , Ludovic Largeau (1) , Roméo Juge (5) , Maryam Massouras (1) , Cristina Balan (8) , Johannes Wilhelmus van der Jagt (5) , Guillaume Agnus (1) , Yves Roussigné (2) , Mihai Gabor (9) , Salim Mourad Chérif (2) , Gianfranco Durin (6) , Shimpei Ono (10) , Jürgen Langer (3) , Damien Querlioz (1) , Dafiné Ravelosona (1, 5) , Mohamed Belmeguenai (2) , Liza Herrera Diez (1)

1 C2N - Centre de Nanosciences et de Nanotechnologies
2 LSPM - Laboratoire des Sciences des Procédés et des Matériaux
3 Singulus technology AG
4 IMM-CNR Unit of Agrate Brianza
5 Spin-Ion Technologies
6 INRiM - Istituto Nazionale di Ricerca Metrologica
7 Polito - Politecnico di Torino = Polytechnic of Turin
8 NEEL - MNM - Micro et NanoMagnétisme
9 Technical University of Cluj-Napoca
10 Central Research Institute of Electrical Power Industry

The magneto-ionic modulation of the Dzyaloshinskii–Moriya interaction (DMI) and the perpendicular magnetic anisotropy (PMA), in W/CoFeB/HfO$_2$ stacks annealed at different temperatures and for varying annealing times, are presented in this work. A large modulation of PMA and DMI is observed in the systems annealed at 390 and 350 °C, whereas no response to voltage is observed in the as-grown samples. A strong DMI is only observed in the samples annealed at 390 °C for 1 h, while PMA is present for all annealing times at temperatures of 390 and 350 °C. Magnetic properties including domain wall velocity improve drastically with increasing the annealing temperature and time, while the magneto-ionic reversibility is increasingly compromised. The changes in PMA and DMI induced by the gate voltages in the samples annealed at 390 °C are permanent, while partial reversibility is only observed for the samples annealed at 350 °C for short times. This dependence of reversibility on post-grown annealing has been associated to the influence of crystallization on ion mobility. These results show that a compromise between the enhancement of the magnetic properties and the magneto-ionic performance could be needed in systems requiring annealing to develop PMA and DMI.

Mots clés: annealing; Dzyaloshinskii-Moriya interaction; magneto-ionics; magneto-ionic reversibility; annealing

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

Rohit Pachat, Djoudi Ourdani, Maria‐andromachi Syskaki, Alessio Lamperti, Subhajit Roy, et al.. Magneto‐ionics in annealed W/CoFeB/HfO2 thin films. Advanced Materials Interfaces, 2022, 9 (36), pp.2200690. ⟨10.1002/admi.202200690⟩. ⟨hal-03787337⟩