Adjustable Current-Induced Magnetization Switching Utilizing Interlayer Exchange Coupling

Electrical current-induced deterministic magnetization switching in a magnetic multilayer structure without any external magnetic field is realized by utilizing interlayer exchange coupling. Two ferromagnetic Co layers, with in-plane and out-of-plane anisotropy, respectively, are separated by a spacer Ta layer, which plays a dual role in inducing antiferromagnetic interlayer coupling, and contributing to the current-induced effective magnetic field through the spin Hall effect. The current-induced magnetization switching behavior can be tuned by premagnetizing the in-plane Co layer. The antiferromagnetic exchange coupling field increases with decreasing thickness of the Ta layer, reaching 630 +/- 5 Oe for a Ta thickness of 1.5 nm. A model is developed to separate the Joule heating and spin-orbit torques caused by the electrical current. The magnitude of the current-induced perpendicular effective magnetic field from spin-orbit torque is 9.2 Oe/(10(7) A cm(-2)). The large spin Hall angle of Ta, opposite in sign to that of Pt, results in a low critical current density of 9 x 10(6) A cm(-2). This approach is promising for the electrical switching of magnetic memory elements without any external magnetic field.