Abstract
Antiferromagnetic insulators are a ubiquitous class of magnetic materials, holding the promise of low-dissipation spin-based computing devices that can display ultra-fast switching and are robust against stray fields. However, their imperviousness to magnetic fields also makes them difficult to control in a reversible and scalable manner. Here we demonstrate a novel proof-of-principle ionic approach to control the spin reorientation (Morin) transition reversibly in the common antiferromagnetic insulator α-Fe2O3 (haematite) – now an emerging spintronic material that hosts topological antiferromagnetic spin-textures and long magnon-diffusion lengths. We use a low-temperature catalytic-spillover process involving the post-growth incorporation or removal of hydrogen from α-Fe2O3 thin films. Hydrogenation drives pronounced changes in its magnetic anisotropy, Néel vector orientation and canted magnetism via electron injection and local distortions. We explain these effects with a detailed magnetic anisotropy model and first-principles calculations. Tailoring our work for future applications, we demonstrate reversible control of the room-temperature spin-state by doping/expelling hydrogen in Rh-substituted α-Fe2O3.
Highlights
As in α-Fe2O3, the original room temperature state of αFe1.97Rh0.03O3 was restored by annealing H-doped samples in 100% Ar or O2 atmospheres, as seen in Fig. 4b and Supplementary-S4
Film growth and H-spillover treatment. α-Fe2O3 and α-Fe1.97Rh0.03O3 epitaxial thin films were grown by pulsed laser deposition (PLD) from stoichiometric targets on single crystalline α-Al2O3 substrates (CrysTec GmbH), using KrF excimer laser (248 nm)
Substrates were cleaned by ultra-sonication in high purity acetone, alcohol and DI Water prior to deposition
Summary
As in α-Fe2O3, the original room temperature state of αFe1.97Rh0.03O3 was restored by annealing H-doped samples in 100% Ar or O2 atmospheres, as seen in Fig. 4b and Supplementary-S4. Pt NS-covered samples were annealed in high purity forming gas (H2/Ar ratio of 5%/95%) at annealing temperatures in the range 150–270 °C. Control annealing experiments were carried in high purity 100% Ar or O2 atmospheres under the same temperature conditions.
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