Nano-Contact Spin-Torque Oscillators as Magnonic Building Blocks

We describe the possibility of using nano-contact spin-torque oscillators (NC-STOs) as fundamental magnonic building blocks. NC-STOs can act as spin wave generators, manipulators, and detectors, and can hence realize all the fundamental functions necessary for fully integrated magnonic devices, which can be fabricated using available CMOS compatible large-scale spin-torque device production processes. We show in particular how a 200 nm sized nano-contact located on an out-of-plane magnetized permalloy “free” magnetic layer can generate spin waves at f≈15 GHz that propagate up to 4 μm away from the nano-contact with wavelength λ=200–300 nm, decay length λ r ≈2 μm and group velocities v g ≈3 μm/ns. We propose that the same type of NC-STOs can be used as spin wave manipulators, via control of the local Gilbert damping, and as spin wave detector using the spin torque diode effect.