| Autor: |
Choi S; Department of Physics and Chemistry, DGIST, Daegu 42988, Republic of Korea., Son J; Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Republic of Korea.; Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea., MacManus-Driscoll JL; Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom., Lee S; Department of Physics and Chemistry, DGIST, Daegu 42988, Republic of Korea. |
| Abstrakt: |
We reversibly control ferromagnetic-antiferromagnetic ordering in an insulating ground state by annealing tensile-strained LaCoO 3 films in hydrogen. This ionic-magnetic coupling occurs due to the hydrogen-driven topotactic transition between perovskite LaCoO 3 and brownmillerite La 2 Co 2 O 5 at a lower temperature (125-200 °C) and within a shorter time (3-10 min) than the oxygen-driven effect (500 °C, tens of hours). The X-ray and optical spectroscopic analyses reveal that the transition results from hydrogen-driven filling of correlated electrons in the Co 3d-orbitals, which successively releases oxygen by destabilizing the CoO 6 octahedra into CoO 4 tetrahedra. The transition is accelerated by surface exchange, diffusion of hydrogen in and oxygen out through atomically ordered oxygen vacancy "nanocomb" stripes in the tensile-strained LaCoO 3 films. Our ionic-magnetic coupling with fast operation, good reproducibility, and long-term stability is a proof-of-principle demonstration of high-performance ultralow power magnetic switching devices for sensors, energy, and artificial intelligence applications, which are keys for attaining carbon neutrality. |
