Second harmonic injection locking of coupled spin torque vortex oscillators with an individual phase access

Fabrication and characterization setup for vortex oscillators

This work is based on circular nanopillars, patterned from an MgO-based MTJ stack (more details presented in the “Methods” section). Each nanopillar acts as a spin torque vortex oscillator (STVO), due to the patterning that induces a vortex magnetic state in the free layer.

To take advantage of the magneto-dipolar interaction, the nanopillars were defined in pairs with an edge-to-edge distance (d_ee) down to 100 nm. Figure 1a shows a scanning electron microscopy (SEM) image of an STVO pair with a nominal d_ee = 100 nm,…