Quantum mechanics

Magnetic field

Spin (aerodynamics)

Magnetization

Spin pumping

Materials science

Ferromagnetism

Spin wave

Excitation

Thermodynamics

Laser

Spinplasmonics

Physics

Optics

Terahertz radiation

Spin Hall effect

Condensed matter physics

Electron

Femtosecond

Spintronics

Spin polarization

Physical review. B./Physical review. B

The mechanism responsible for the generation of optically induced spin currents upon femtosecond laser-pulse excitation of ultrathin ferromagnetic layers is still a heavily debated topic. In this paper, the authors study the phase of spin-current induced terahertz spin waves in noncollinear bilayer structures to probe spin currents in Fourier space. They measure a significant laser-pulse energy dependence of the spin-wave phase, which is quantitatively consistent with a spin current that is proportional to the time derivative of the magnetization.

Probing optically induced spin currents using terahertz spin waves in noncollinear magnetic bilayers