Spin Torque Oscillator Maser

An oscillator comprising, a cavity wherein the cavity comprises an electrical conductor. The oscillator comprising an electrical insulator disposed on a surface of the cavity; and a heterostructure disposed on a surface of the electrical insulator and having a first end and a second end, the heterostructure comprising one or more spin current source layers and one or more magnetic material layers. In response to an electrical current passed through the spin current source, an oscillation occurs in a plurality of magnetic domains of the magnetic material, wherein the oscillations have substantially the same phase.