Enhanced Magnetization in CoFe2O4 Through Hydrogen Doping

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 mu(B)/u.c in CoFe2O4 (CFO) through ionic liquid gating induced hydrogen doping. The intercalated hydrogen ions lead to both distinct lattice expansion of approximate to 0.7% and notable Fe valence state reduction through electron doping, in which approximate to 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.