THERMOELECTRIC-POWER OF DEGENERATE MAGNETIC SEMICONDUCTOR

The thermoelectric power α has been measured for degenerate magnetic semiconductor Sn1-xMnxTe (x0.19) with carrier concentration of (1–8) ×1020cm-3 over a wide range of temperature 300–4.2 K. The α-T curves of undoped crystals (x = 0) can be explained by the Rogers theoretical expression for α which takes account of intravalley acoustic phonon scattering and two-valence-band model, together with the variation of the band gap and carrier concentration with temperature. In the Mn-doped crystals α has a contribution from ionized impurity scattering. In addition, their α-T curves show a maximum near 20–25 K associated with magnetic ordering. The anomalous thermopowers are compared with the Kasuya theory, with the total angular momentum J = 2 and paramagnetic Curie temperature θ' = 30–40 K. Also we found a small anomaly around 150 K arising from a displacive phase transition of the host lattice. © 1979, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.