Published the July 11, 2022

Magneto-Ionics in Annealed W/CoFeB/HfO2 Thin Films

The magneto-ionic modulation of the Dzyaloshinskii–Moriya interaction (DMI) and the perpendicular magnetic anisotropy (PMA), in W/CoFeB/HfO2 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.

Magneto-Ionics in Annealed W/CoFeB/HfO2 Thin Films
Rohit Pachat1, Djoudi Ourdani2, Maria-Andromachi Syskaki3, Alessio Lamperti4, Subhajit Roy1, Song Chen5, Adriano Di Pietro6, Ludovic Largeau1, Roméo Juge5, Maryam Massouras1, Cristina Balan7, Johannes Wilhelmus van der Jagt5, Guillaume Agnus1, Yves Roussigné2, Mihai Gabor8, Salim Mourad Chérif2, Gianfranco Durin6, Shimpei Ono9, Jürgen Langer3, Damien Querlioz1, Dafiné Ravelosona1,5, Mohamed Belmeguenai2, Liza Herrera Diez1

1 Centre de Nanosciences et de Nanotechnologies, CNRS, Université Paris-Saclay, Palaiseau, 91120 France
2 Laboratoire des Sciences des Procédés et des Matériaux, CNRS-UPR 3407, Université Sorbonne Paris Nord, Villetaneuse, 93430 France
3 Singulus Technology AG, Hanauer Landstrasse 103, 63796 Kahl am Main, Germany
4 IMM-CNR, Unit of Agrate Brianza, Via C. Olivetti 2, Agrate Brianza, 20864 Italy
5 Spin-Ion Technologies, 10 Boulevard Thomas Gobert, Palaiseau, 91120 France
6 Istituto Nazionale di Ricerca Metrologica, Strada delle Cacce 91, Torino, 10135 Italy
7 Univ. Grenoble Alpes, CNRS, Institut Néel, Grenoble, 38000 France
8 Center for Superconductivity, Spintronics and Surface Science, Physics and Chemistry Department, Technical University of Cluj-Napoca, Cluj-Napoca, RO-400114 Romania
9 Central Research Institute of Electric Power Industry, Yokosuka, Kanagawa, 240-0196 Japan

Adv. Mater. Interfaces 2022, 2200690

Contact : Liza Herrera - Diaz

Figure : 1. a) Schematic of the structure of the ionic-liquid gate device and pMOKE signal under an out-of-plane magnetic field (μ0Hz) of the b) as-grown, and c) annealed S2 sample under different gate voltages and gating times.