How do magnetic fields affect the conductivity of some semiconductors?

Magnetic fields influence the conductivity and electrical behavior of semiconductors primarily through two phenomena: the Hall effect and magnetoresistance.

The Hall Effect

When a semiconductor carrying an electric current is placed in a magnetic field perpendicular to the current flow, the Lorentz force acts on the moving charge carriers (electrons and holes). This force deflects the carriers to one side of the material, creating a transverse potential difference known as the Hall voltage. This effect is significant in semiconductors because it allows researchers to determine the density and mobility of charge carriers, as well as identify whether electrons or holes predominate in the conduction process.12

Magnetoresistance

Magnetoresistance refers to the change in a material's electrical resistance when subjected to an external magnetic field. In some materials, this change can be extreme, a phenomenon known as colossal magnetoresistance. By altering the resistance of a semiconductor, magnetic fields can effectively modulate the material's conductivity, a property utilized in various electronic applications, such as high-capacity data storage read heads.34