Structural transformation-induced magnetic ordering in degenerate magnetic semiconductors

Electrical properties and molar specific heats have been measured in the temperature range 2–300 K of Bridgman-grown Sn_1–xCr_xTe crystals. In addition to the paramagnetic-to-ferro or ferrimagnetic transition temperatureT_c(= 150–300 K), in this magnetic system there is another characteristic temperatureT_AHE (= 4–5 K), above which the anomalous Hall effects vanish and around which the specific heats show a small peak, indicating an extra magnetic transition. The low-temperature transition is considered as induced by a cubic-to-rhombohedral structural phase transition of the host SnTe crystal occurring at a critical temperature ofT_s (= 80–100 K). Data on the isothermal annealing of these crystals are also presented.