Multi-state electromagnetic phase modulations in NiCo2O4 through cation disorder and hydrogenation

Abstract

One focal challenge in engineering low-power and scalable all-oxide spintronic devices lies in exploring ferromagnetic oxides with perpendicular magnetic anisotropy (PMA) and electronic conductivity while exhibiting tunable spin states. Targeting this need, spinel nickel cobaltite (NiCo2O4 , NCO), featured by ferrimagnetically metallic ground state with strong PMA, emerges as a promising candidate in the field of oxide spintronics. Here, we unveil multi-state electromagnetic phase modulations in NCO system through controllable cation disorder and proton evolution, extensively expanding electromagnetic phase diagram. The cation disorder in NCO is identified as a critical control parameter for kinetically adjusting the proton evolution, giving rise to emergent intermediate hydrogenated states. Hydrogen incorporation reversibly drives structural phase transformation and electromagnetic state evolutions in NCO, with rich spin-dependent correlated physics. Our work not only establishes NCO as a versatile platform for discovering spin-dependent physical functionality but also extends the horizons in materials design for state-of-the-art spintronic devices.