Transport, magnetic, optical and thermodynamic properties of Bi2−xMnxSe3 single crystals

Single crystals of Bi2Se3 doped with Mn (cMn=0–3.0×1019 atoms/cm3) were grown using a modified Bridgman method. The prepared samples were characterized by X-ray diffraction and chemical analysis, and subsequently investigated by measurements of the reflectivity in the plasma-resonance-frequency region and by measurements of the temperature and magnetic field dependencies of the magnetization, specific heat and transport properties. The results show that incorporation of Mn atoms in the crystal structure leads to an increase of the free-electron concentration, as well as to an increase of the mobility of the free electrons. The Mn2+ valence state of the Mn ions has been established by magnetic measurements, which show a different behavior than the scenario proposed by Choi et al. [J. Choi, H.-W. Lee, B.-S. Kim, S. Choi, J. Choi, J. H. Song and S. Cho, J. Appl. Phys. 97, 10D324 (2005)]. The observations are explained in terms of the point-defect model, which is based on the idea that the Mn impurities create substitutional defects of the Mn′BiMn′Bi-type and reduce the concentration of antistructure Bi′SeBi′Se defects.