Thermal Hall effect
Encyclopedia
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 dubbed 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 (known as the Senftleben-Beenakker effect
).
Measurements of the thermal Hall conducitivity are used to distinguish between the electronic and lattice contributions to thermal conductivity. These measurements are especially useful when studying superconductors.
Hall effect
The Hall effect is the production of a voltage difference across an electrical conductor, transverse to an electric current in the conductor and a magnetic field perpendicular to the current...
. 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
Thermal conductivity
In physics, thermal conductivity, k, is the property of a material's ability to conduct heat. It appears primarily in Fourier's Law for heat conduction....
when placing a conductor in a magnetic field
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...
.
A thermal Hall effect has also been measured in a paramagnetic insulator and dubbed the "phonon Hall effect." In this case, there are no charged currents in the solid so the magnetic field cannot exert a Lorentz force
Lorentz force
In physics, the Lorentz force is the force on a point charge due to electromagnetic fields. It is given by the following equation in terms of the electric and magnetic fields:...
. An analogous thermal Hall effect for neutral particles exists in polyatomic gases (known as the Senftleben-Beenakker effect
Senftleben-Beenakker effect
The Senftleben-Beenakker effect is the dependence on a magnetic or electric field of transport properties of polyatomic gases. The effect is caused by the precession of the dipole of the gas molecules between collisions...
).
Measurements of the thermal Hall conducitivity are used to distinguish between the electronic and lattice contributions to thermal conductivity. These measurements are especially useful when studying superconductors.