DISPERSION OF THE VOIGT EFFECT IN THE MAGNETIC SEMICONDUCTORS CD1-XMNXTE

Spectral measurements of the Voigt birefringence Delta n were performe d for the cubic magnetic semiconductor Cd1-xMnxTe (0 less than or equa l to x less than or equal to 0.52) in order to investigate how the exc hange interaction of Mn2+ ions with itinerant electrons depends on the electron wave vector. It was determined that Delta n/x(2) is independ ent of x and the magnetic field direction, i.e., the effect is due to the Mn2+ ions and is isotropic. Below the band gap edge the dispersion of the birefringence Delta n can be described well in all samples by the unusual dependence Delta n similar to(E-g - ($) over bar omega)(-3 .5). This can be explained by a decrease of the exchange interaction o f Mn2+ ions with itinerant electrons with increasing distance from the center of the Brillouin zone. (C) 1998 American Institute of Physics. [S0021-3640(98)01008-1]