What is magnonics?

What is a spin wave?

Spins obey similar physical laws as spinning tops: If a spinning top receives a shock perpendicular to its axis of rotation, it does not flip over, but its axis of rotation starts to rotate. We call this phenomenon precession.

Spins also begin to precess when deflected from their resting position. Unlike the spinning top, however, this deflection is not achieved by a mechanical impact, but by the brief effect of a magnetic field on the spin. In a magnet in which spins are arranged in a lattice-like structure, the precession of a spin is transmitted to its neighbors and propagates through the magnet. We speak of a spin wave.

What is a Magnon?

In modern physics, each wave can be associated with a specific particle. The best known is the light particle, the photon. The magnon is the particle assigned to spin waves.

What is magnonics?

Magnonics deals with spin waves and their propagation in magnetic solids. Similar to spintronics, spin waves as information carriers offer the advantage that electrons do not have to migrate through the solid during data transmission, which means that only very small losses occur. Due to the low losses, very little heat is emitted during the flow of information, thus, this should allow for constructing components, e.g. for computers, that are smaller, more efficient and faster than existing chips.

Spin waves offer an additional advantage: As with water waves, two spin waves overlap so that wave crests and troughs can cancel out or amplify each other. This phenomenon is called interference (see left graph).

Whether a cancellation or an amplification occurs at a certain point depends on the phase of the waves, i.e. their distance or delay from one another (see graph on the right).

In the spin-wave computer, information can be transmitted and processed in this phase of the waves. This offers a variety of new possibilities for the realization of components for circuits.