Non-collinear coupling across RuCo and RuFe alloys

Abstract: Spintronic applications, which rely on spin torques for operation, would greatly benefit from a non-collinear alignment between magnetizations of adjacent ferromagnetic layers for maximum performance and reliability. We demonstrate that such an alignment can be created and controlled by coupling two ferromagnetic layers across magnetic coupling layers. These coupling layers consist of a non-magnetic material, Ru, alloyed with ferromagnetic elements of Co or Fe. Changing the composition and thickness of the coupling layer enables control of the relative angle between the magnetizations of ferromagnetic layers between 0 and 180 degrees. The onset of the non-collinear alignment between ferromagnetic layers coincide with the advent of magnetic order in the coupling layer. This study will map the range of concentrations and thicknesses of RuCo and RuFe coupling layers that give rise to non-collinearity between Co layers.