Field-free spin-orbit torque switching with enhanced switching ratio in Co/Ni multilayers by laterally broken symmetry induced by He ion bombardment

초록

Current-induced spin-orbit torque (SOT) provides efficient magnetization control in spintronic devices. However, applications of SOTare limited, asdeterministic switching of perpendicular magnetization typically requires an external magnetic field. To overcome this, various approaches havebeen developed for field-free SOT switching, including lateral symmetry breaking to generate out-of-plane SOT. In this study, we demonstrate field-free perpendicular magnetization switching with a 4-fold enhancement of the switching ratio in [Co/Ni] ferromagnetic multilayers through lateralsymmetry modulation of magnetic anisotropy via He ion-irradiation. This approach offers a complementary-metal-oxide-semiconductor integrationfriendly solution for future SOT-based spintronic devices.(c) 2024 The Author(s). Published on behalf of The Japan Society of Applied Physics byIOP Publishing Ltd

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