Nernst effect

This effect is quantified by the Nernst coefficient ${\displaystyle \nu }$, which is defined to be

${\displaystyle \nu =\frac{E_y}{B_z}\frac{1}{{\mathrm{\partial }}_{x}T}}$

where ${\displaystyle E_y}$ is the y-component of the electric field that results from the magnetic field's z-component ${\displaystyle B_z}$ and the x-component of the temperature gradient ${\displaystyle {\mathrm{\partial }}_{x}T}$.

The reverse process is known as the Ettingshausen effect and also as the second Nernst–Ettingshausen effect.

Physical picture

Mobile energy carriers (for example conduction-band electrons in a semiconductor) will move along temperature gradients due to statistics and the relationship between temperature and kinetic energy. If there is a magnetic field transversal to the temperature gradient and the carriers are electrically charged, they experience a force perpendicular to their direction of motion (also the direction of the temperature gradient) and to the magnetic field. Thus, a perpendicular electric field is induced.