Spin can be generated from the heating. Important mechanisms for this charge-spin conversion are the spin-Seebeck effect, spin-dependent Seebeck effect, and anomalous Nernst effect. Heating can be done in various ways, such as Joule heating, laser pulse, or electric pulse.
When heat current flows through the metallic ferromagnet, the spin-dependent Seebeck effect induces a spin current. This spin current can be transferred to other layers and leads to spin accumulation and spin-transfer torque.
Related works:
Spin-dependent Spin Seebeck effect: https://www.nature.com/articles/nphys3355
Demagnetization-driven spin generation: https://www.nature.com/articles/ncomms5334
In particular materials, magnetic phase-transition occurs by heating. We expect that a sudden phase transition can generate a spin current. Therefore, by controlling the phase transition, we can control the spin current.
Metallic ferromagnet has energy carriers of electron, magnon, and phonon. When energy of the electron bath is transferred to the magnon and phonon baths, angular momentum can be exchanged among them. The exchange rate will be determined by the coupling parameter.
Related works:
Spin relaxation in metallic ferromagnet: https://doi.org/10.1016/j.jmmm.2020.166945
Electron-magnon and electron-phonon coupling: https://doi.org/10.1016/j.jmmm.2020.167156
