Manipulation of Magnetization Switching by Ultrafast Spin-Polarized Hot-Electron Transport in Synthetic Antiferromagnet

Uncovering the physical mechanisms that govern ultrafast charge and spin dynamics is becoming indispensable both at the fundamental level and to develop future spin-based electronics. Recently it has been shown that femtosecond pulsed-laser excitation of magnetic thin films produces intense and ultrafast spin-polarized hot electrons, thus attracting a lot of attention. While spin-polarized hot electrons are known to play a pivotal role in the ultrafast laser-induced demagnetization, their effect on magnetization switching remains an open issue. This study uncovers the effect of spin-polarized hot electrons generated by laser excitation on magnetization switching in a Co/Pt based perpendicular magnetic anisotropy-based synthetic antiferromagnet (p-SAF) using the time-resolved magneto-optical Kerr effect. It has been found that, at low pump fluence, the equivalent magnetic field generated by the hot-electron spin current plays a dominant role in assisting the magnetization switching of the lower layer in the antiferromagnetic configuration, while the strong thermal stability of the Ruderman Kittel Kasuya Yosida exchange interaction inhibits the further weakening of the switching field at high pump fluence. This study provides a viable way to control the magnetization switching of the antiferromagnetically exchange-coupled systems for spintronic applications with ultrafast control of the information operation.