The peculiarities of the exchange interaction between the carrier spin and
localized spin moments of magnetic ions near the semimetal-semiconductor tr
ansition have been studied in a semimagnetic quaternary solid solution syst
em, Hg1-x-yCdxMnySe (x = 0.10, y = 0.02, E-g = 45 meV), by means of Shubnik
ov-de Haas oscillations.
The measurements show that the exchange 'constant' alpha is actually a some
what complicated function <(alpha)over tilde> of energy gap E-g and electro
n concentration, which changes from negative values (<(alpha)over tilde>N-0
= -0.15 eV) at lower electron concentration to positive values (<(alpha)ov
er tilde>N-0 = 0.28 eV) at higher electron concentration, values which are
more typically associated with wide-gap semimagnetic semiconductors.