Thermal Hall effect
The thermal Hall effect is the thermal analog of the Hall effect. Here, a thermal gradient is produced across a solid instead of an electric field. When a magnetic field is applied, an orthogonal temperature gradient develops.
For conductors, a significant portion of the thermal current is carried by the electrons. In particular, the Righi–Leduc effect describes the heat flow resulting from a perpendicular temperature gradient and vice versa, and the Maggi–Righi–Leduc effect describes changes in thermal conductivity when placing a conductor in a magnetic field.
A thermal Hall effect has also been measured in a paramagnetic insulator and called the "phonon Hall effect". In this case, there are no charged currents in the solid, so the magnetic field cannot exert a Lorentz force. An analogous thermal Hall effect for neutral particles exists in polyatomic gases.
Measurements of the thermal Hall conductivity are used to distinguish between the electronic and lattice contributions to thermal conductivity. These measurements are especially useful when studying superconductors.
