Low-Temperature Electrical Conductivity in Mn-Doped Bi0.9Sb0.1 Solid Solutions

Abstract

The temperature dependence of the specific electrical resistance of the semiconductor single-crystal Bi_0.9Sb_0.1 solid solution doped with 1% Mn is shown to have, with a decrease in temperature, the activation character of the band electrical conductivity with the activation energy 10 meV that is changed at temperatures below 20 K for the “metallic” character determined by the electrical conductivity (EC) over the impurity band. The activation EC in single-crystal Bi_0.9Sb_0.1 solid solutions doped with 3% Mn is revealed to disappear and the “metallic” character of EC is observed over entire temperature range under study 5‒300 K with a peculiarity at low temperatures near 25 K reacting on external magnetic fields. It is assumed that, at high concentrations of doping with Mn atoms, a wide impurity band appears overlapping the whole forbidden band, and the observed peculiarities are related to spin fluctuations that take plays when ordering spins of magnetic Mn atoms. The mobility and the charge carrier concentration are evaluated.