  Magnetic droplets, a class of highly non-linear magnetodynamical solitons,
can be nucleated and stabilized in nanocontact spin-torque nano-oscillators
where they greatly increase the microwave output power. Here, we experimentally
demonstrate magnetic droplets in magnetic tunnel junctions (MTJs). The droplet
nucleation is accompanied by a power increase of over 300 times compared to its
ferromagnetic resonance modes. The nucleation and stabilization of droplets are
ascribed to the double-CoFeB free layer structure in the all-perpendicular MTJ
which provides a low Zhang-Li torque and a high pinning field. Our results
enable better electrical sensitivity in the fundamental studies of droplets and
show that the droplets can be utilized in MTJ-based applications.
