| Affiliation: | 1. State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, 100084 China;2. Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, 200240 China;3. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190 China;4. Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Washington, 99354 USA;5. Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu, 30010 Taiwan;6. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California, 94720 USA;7. Department of Physics, Durham University, Durham, DH1 3LE UK;8. Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu, 30010 Taiwan
Department of Materials Science & Engineering, National Tsing Hua University, Hsinchu, 30013 Taiwan |
| Abstract: | Magnetic spinel oxides have attracted extensive research interest due to their rich physics and wide range of applications. However, these materials invariably suffer suppressed magnetization, due to structural imperfections (e.g., disorder, anti-site defects, etc.). Herein, a dramatic enhanced magnetization is obtained with an increasement of 5 µB/u.c in CoFe2O4 (CFO) through ionic liquid gating induced hydrogen doping. The intercalated hydrogen ions lead to both distinct lattice expansion of ≈0.7% and notable Fe valence state reduction through electron doping, in which ≈17% Fe3+ is reduced into Fe2+. These facts collectively trigger a site-specific spin-flip on tetrahedrally coordinated Co2+ sites that enhances the net ferrimagnetic moment nearly to its theoretical maximum for perfect CFO. |
