Chiral phonons and electrical resistivity of ferromagnetic metals at low temperatures

At low temperatures all metals have a predominant quadratic variation of the electrical resistivity with temperature. This is due to electron-electron scattering and, in magnetic materials, also due to electron scattering with spin waves. However, for ferromagnets an extra linear variation is measured around liquid-helium temperatures.

For a long time, this had been an unsolved problem, with attempts to explain it not coinciding with the experiments. Revisiting the assumptions of the standard theory, I found a missing component: a spin-flip scattering mechanism of conduction electrons in ferromagnets arising from their interaction with the internal magnetic induction. This interaction is mediated by chiral modes of the crystal lattice vibrations: phonons with spin-1.

By taking this mechanism into account, I could show that its contribution to the electrical resistivity varies linearly with temperature, with a rate coinciding with the old measurements for iron, cobalt and nickel.