Peculiarities of the exchange interaction in narrow-gap Hq_(1-x-y)Cd_xMn_ySe

摘要

The peculiarities of the exchange interaction between the carrier spin and localized spin moments of magnetic ions near the semimetal-semiconductor transition have been studied in a semimagnetic quaternary solid solution system, Hg_(1-x-y)Cd_xMn_ySe (x = 0.10, y = 0.02, E_g = 45 meV), by means of Shubnikov-de Haas oscillations. The measurements show that the exchange ‘constant' α is actually a somewhat complicated function d of energy gap E_g and electron concentration, which changes from negative values (αN_0 =-0.15 eV) at lower electron concentration to positive values (αN_0 = 0.28 eV) at higher electron concentration, values which are more typically associated with wide-gap semimagnetic semiconductors.