Voltage-assisted all-optical switching in magnetic tunnel junctions based on Tb/Co multilayers

This work investigates the influence of bias voltage on the optical switching behavior of a Tb/Co-based Magnetic Tunnel Junction (MTJ) in an 80-nm diameter pillar device. The experimental results demonstrate enhanced switching performance at high bias voltage, with a maximum switching probability achieved at bias voltage values of 200 and 400 mV. At high bias, Joule heating effect reduces the effective magnetic anisotropy of the pillar device, thereby favoring in-plane magnetization precession, lowering the switching threshold, and expanding the toggle switching window. The optical switching exhibits a pronounced asymmetry, showing a favorable switching under negative voltage polarity. Under this polarity, tunneling electrons are injected toward the top electrode, causing the decrease of magnetic anisotropy in the Tb/Co-based free layer and, therefore, facilitating the magnetization reversal at a laser pulse. The thermal analysis of All-Optical Switching (AOS)-MTJ devices under opposite bias polarities shows a temperature difference of 5–10 K, depending on the pillar diameter. These findings demonstrate voltage-selective control for multiple AOS devices integrated on the same chips, enabling an application for CMOS-compatible magneto-photonic memory.