Abstract. We show experimentally that the Faraday rotation which is the rotation of the light polarization during transmission of linearly polarized light through a ferromagnet, has its analogue in experiments with spin-polarized electrons: the spin-polarization vector precesses around the direction of the magnetization. For low-energy electrons the precession angle per unit length is two orders of magnitude larger compared to the one observed with light. It is a direct measure of the elusive exchange energy as it depends on the energy of the electrons. We believe that applying this phenomenon will offer new prospects of studying magnetism.

Received 3 March 1999
Published 24 May 1999