Characterization of interlayer interactions in magnetic random access memory layer stacks using ferromagnetic resonance

Ferromagnetic resonance spectroscopy is used to determine magnetic interactions in layer stacks designed for orthogonal spin-transfer magnetic random memory devices. The stacks have layers with different anisotropy directions and coupling, consisting of a perpendicularly magnetized polarizer, an in-plane magnetized free layer, and an in-plane magnetized exchange biased synthetic antiferromagnetic layer. The oscillatory exchange coupling strength in the synthetic antiferromagnet was measured along with its exchange bias. The free layer properties were also determined. It is demonstrated that this one integrated measurement technique is able to provide quantitative measurements of key magnetic parameters in a complex layer stack, which is a prerequisite for high turn-around device materials characterization and optimization.