SPIN SATURATION OF THE RANDOM ANTIFERROMAGNET (CD,MN)TE IN MAGNETIC-FIELDS TO 150-T

Spin alignment of magnetic Mn2+ ions in the random antiferromagnet Cd(1-x)Mn(x)Te is studied in high magnetic fields. Faraday-rotation measurements at T approximately 10 K were made up to 150 T for magnetic concentrations ranging from x = 0.1 to 0.6. For x = 0.1 and 0.2 the applied fields are large enough to overcome the internal antiferromagnetic exchange fields, leading to total spin saturation, <S(Z)> = 5/2, at B = 80 and 130 T, respectively. For higher concentrations the spin alignment becomes increasingly difficult due to the increasing number of neighboring spins. A mean-field model that takes into account the random site occupation self-consistently fits the measured field and concentration dependencies of <S(Z)> remarkably well.