The coefficient of the thermoelectric power ( S) measured in variable magnetic fields ( B) is called magnetothermopower. This physical quantity can provide very valuable complementary information concerning details of electronic band structure. In comparison with the magnetoresistivity, the magnetothermopower is not sensitive to a uniform change of mobility of conduction electrons by the Lorentz force. The magnetothermopower of metallic materials basically depends on a relative change of the mobility of conduction electrons with different energy near the Fermi surface.

The effect of magnetic fields on thermopower is important also from a practical point of view. Thermocouples are widely used as temperature sensors. Therefore, in low-temperature thermometry in equipment with strong magnetic fields, such as research cryostats with superconducting magnets, a knowledge of the sensitivity of a thermocouple to the magnetic field is essential. Another significant and expanding field for the application of thermoelectric phenomena is thermoelectric heat energy conversion and thermoelectric cooling. It is known that the thermoelectric efficiency of some materials can be considerably enhanced in a magnetic field (examples are bismuth-based alloys which are used for low-temperature refrigeration).