Antiferromagnetic Droplet Soliton in a Nano-Contact Spin-Transfer Torque Oscillator

We demonstrate that a spin current flowing through a nano-contact into a uniaxial antiferromagnet with first- and second-order anisotropy can excite a self-localized dynamic magnetic soliton, known as a spin-wave droplet in ferromagnets. In this case, the frequency of the Néel vector precession lies below the antiferromagnetic resonance and decreases with the applied current. Above a certain threshold, the soliton mode disappears, and the oscillator instead emits spin waves propagating in the antiferromagnetic layer.