Magnetic interface profiles in amorphous spin-orbit torque switching structures

Spin-orbit torque-induced (SOT) magnetization switching is an important effect in spintronic applications such as magnetic random access memories, and spin logic devices. It is a very active topic of research and a number of different materials systems have been studied. SOT switching devices are layered structures composed of a thin magnetic layer (M) such as TbCo adjacent to a polycrystalline heavy metal (HM) layer such as Pt, Ta or W. The heavy metal layer is used to supply a spin current which generates the torque to switch the magnetic layer. A figure of merit for SOT switching is the switching efficiency which depends on the properties of the HM and the spin transport across the interface. The interface between the two layers is therefore critical. At the interface between a magnetic and non-magnetic material it is known that a magnetization can be induced in the non-magnetic material and this is known as the magnetic proximity effect. Despite its importance the magnetic proximity effect is often not considered in SOT switching studies. The objective is to determine the magnetization profile of HM|M multilayers with PNR measurements, with WSi, TaSi, and Pt as the HM and CoAlZr as the magnetic layer. This will allow us to determine whether the magnetic interfaces are sharp or whether the magnetization varies smoothly across the interface into the HM layer due to the magnetic proximity effect.