MAGNETIC SPECIFIC HEAT STUDY OF THE COMPETITION BETWEEN FERRO- AND ANTIFERROMAGNETIC SPIN-SPIN EXCHANGE INTERACTIONS IN PbSnMnTe

摘要

Magnetic contribution to the specific heat, magnetic susceptibility and Hall effect are experimentally studied in Pb_(1-x-y)Sn_yMn_xTe semimagnetic semiconductors with y = 0.72 and x = 0.08 and with different carrier concentrations 10~(20) ≤ p ≤ 10~(21) cm~(-3). The ferromagnetism observed in crystals with p > 3 x 10~(20) cm~(-3) breaks down with a decreasing concentration of carriers due to an increasing competition between Ruderman-Kittel-Kasuya-Yoshida and superexchange interactions.