Quantum mechanics

Magnetic field

Spin (aerodynamics)

Precession

Magnetization

Statistics

Realization (probability)

Antiferromagnetism

Thermodynamics

Physics

Amplitude

Mathematics

Optics

Terahertz radiation

Condensed matter physics

Excited state

Micromagnetics

Physical review. B./Physical review. B

The realization of THz sources is a fundamental aspect for a wide range of applications. Over different approaches, compact THz oscillators can be realized taking advantage of dynamics in antiferromagnetic (AFMs) thin films driven by spin-Hall effect. Here we perform a systematic study of these THz oscillators within a full micromagnetic solver based on the numerical solution of two coupled Landau-Lifshitz-Gilbert-Slonczewski equations, for the case of ultra-thin films, i.e. when the N\'eel temperature of an AFM is substantially reduced. We have found two different dynamical modes depending on the strength of the Dzyaloshinskii-Moriya interaction (DMI). At low DMI, a large amplitude precession is excited where both the magnetizations of the sublattices are in a uniform state and rotate in the same direction. At large enough DMI, the ground state of the AFM becomes non-uniform and the antiferromagnetic dynamics is characterized by ultrafast domain wall motion.

Micromagnetic modeling of terahertz oscillations in an antiferromagnetic material driven by the spin Hall effect