spinwelle

Spinwelle, or spin wave, is a propagating disturbance of the magnetic order in a magnetically ordered material. It is a collective precession of the spins that travels through the lattice as a wave. In a ferromagnet or antiferromagnet, small deviations from the ground-state spin alignment propagate via the exchange interaction, and the quanta of these excitations are called magnons.

Spin waves exhibit dispersion: the frequency depends on the wave vector and on material parameters such as the exchange stiffness, the saturation magnetization, and the external or anisotropy fields. At long wavelengths, dipolar (magnetostatic) interactions shape the spectrum; at short wavelengths, exchange interactions dominate, yielding higher frequencies and steeper dispersion.

Experimentally, spin waves are probed by inelastic neutron scattering, Brillouin light scattering, and, for uniform precession, ferromagnetic resonance. Materials of interest include metallic ferromagnets (iron, cobalt, nickel) and ferrimagnetic insulators such as yttrium iron garnet (YIG), which supports low-damping spin waves suitable for magnonics.

Spin waves underpin magnonics, a field exploring wave-based information processing and signal routing with potentially lower energy dissipation than charge-based electronics. They also play a role in spintronics as carriers of spin information and in studies of fundamental magnetism.

Note: the German term spinwelle is commonly used in German-language literature; in English, the term spin wave or magnon describes the same phenomenon.