Magnetic-Field-Induced Large OER Enhancement in Co-Based Ferrimagnetic Thin Films

Here, CoTb ferrimagnetic thin films with strong perpendicular magnetic anisotropy (PMA) are used to investigate the relationship between magnetic ordering and OER kinetics. Under a 300 mT magnetic field, the onset potential decreases by ∼96 mV and the Tafel slope by ∼15.1 mV·dec^–1, accompanied by reduced charge-transfer resistance.

The enhanced OER activity is strongly correlated with magnetic-state regulation and largely retained after field removal. Tb-mediated 3<i>d</i>–4<i>f</i> exchange and strong PMA contribute to regulating and retaining the Co magnetic state, which may influence interactions between Co active sites and oxygen intermediates. This nonvolatile magnetic state may eliminate the need for continuous field application, potentially reducing energy consumption.