Spin torque oscillator having multiple fixed ferromagnetic layers or multiple free ferromagnetic layers

A method of making a spin torque oscillator configured to generate microwave electrical oscillations without the use of a magnetic field external thereto, comprising:

• providing a spin torque oscillator having a plurality of input nanopillars;
• providing a free FM layer;
• providing a tunnel junction disposed on the free FM layer;
• insulating the plurality of nanopillars from one another;
• disposing the plurality of nanopillars on the tunnel junction, the plurality of nanopillars further including an output nanopillar and respective fixed magnetic layers.

A system comprising an integrated circuit including:

• a device layer;
• a plurality of inter-layer dielectric layers disposed on the device layer;
• a plurality of metal lines interleaved between the inter-layer dielectric layers;
• a spin torque oscillator disposed between two of the plurality of metal lines such that the metal lines correspond to electrodes thereof, the spin torque oscillator being configured to generate microwave electrical oscillations without the use of a magnetic field external thereto, the spin torque oscillator having:
• a plurality of input nanopillars;
• a free FM layer;
• and
• a tunnel junction disposed on the free FM layer;
• wherein the plurality of nanopillars are insulated from one another and disposed on the tunnel junction, the plurality of nanopillars further including an output nanopillar and respective fixed magnetic layers.