Current-induced field-free magnetization switching in CoFeB/Cu/CoFeB pseudo-spin-valves

Emergent orbital torque (OT) from the orbital Hall effect of light metals has significant potential for electrical control of magnetization. In this study, the electric manipulation of a most basic spintronic nanostructure, the pseudo-spin-valve (PSV) CoFeB/Cu/CoFeB, is demonstrated with the Cu spacer acting as an effective orbital current source. In the absence of an external magnetic field, the bottom and top CoFeB layers exhibit opposite switching behavior during current scanning, resulting in a current-dependent giant magnetoresistance (GMR) curve that is inverted relative to the conventional field-driven PSV-GMR curve. The OT-induced field-like effective field, evaluated through the horizontal shift of the conventional GMR curve under different currents, is comparable to those of the heavy metal-based structures Pt/CoFeB and Ta/CoFeB. In addition to emphasizing the significance of orbital transport in all-light-metal structures, the finding introduces a different degree of freedom to energy efficient spin-valve devices.