A magnon is a quasiparticle, a collective excitation of the spin structure of an electron in a crystal lattice.
Magnons carry a fixed amount of energy and lattice momentum, and are spin-1, indicating they obey boson behavior.
The concept of a magnon was introduced in 1930 by Felix Bloch[1] in order to explain the reduction of the spontaneous magnetization in a ferromagnet.
The quantitative theory of magnons, quantized spin waves, was developed further by Theodore Holstein and Henry Primakoff,[2] and then by Freeman Dyson.
[3] Using the second quantization formalism they showed that magnons behave as weakly interacting quasiparticles obeying Bose–Einstein statistics (bosons).
[5] Direct experimental detection of magnons by inelastic neutron scattering in ferrite was achieved in 1957 by Bertram Brockhouse.
[8] In 2015 Uchida et al. reported the generation of spin currents by surface plasmon resonance.
For low enough temperatures, the local atomic magnetic moments (spins) in ferromagnetic or anti-ferromagnetic compounds will become ordered.
Microwave pumping can be used to excite spin waves and create additional non-equilibrium magnons which thermalize into phonons.