The analysis of spin current source in current-induced switching of the magnetization in T-type magnetic structures

The schemes for addressing the obstacle of field-free switching driven by spin–orbit torque (SOT) have aroused the interest of spintronic community, for their rich physical phenomena. Here, we utilized the in-plane CoFeB(→)/W/perpendicular CoFeB(↑) design, a magnetic structure of the so-named T-type, to achieve field-free switching in a series of samples with different thicknesses. Through the second-harmonic measurement and the loop-shift method, we get a high effective spin Hall angle ∼0.149 in a 1 nm thin W spacer, indicating that the ultrathin W heavy metal still has sufficient application potential, which can function as both a coupling spacer and a spin source layer. Furthermore, we demonstrate that ferromagnetic materials can also serve as a prominent spin source that facilitates SOT-driven magnetization switching, employing the spin anomalous Hall effect. This investigation contributes valuable insights for the design and integration of spintronic devices in the advancement of sophisticated microelectronics.