Ferromagnetism in new diluted magnetic semiconductor Bi2-xFexTe3

Single crystals of the new diluted magnetic semiconductors of p-Bi2-xFexTe3 (0 less than or equal to x less than or equal to 0.08) and n-Bi2-xFexSe3 (0 less than or equal tox less than or equal to 0,04) have been produced. Magnetization and magnetic susceptibility have been measured in the temperature interval 2-300 K. The ferromagnetic phase was found in p-Bi2-yFeyTe3 at a temperature T-c which increases with Fe content v up to T-c = 12 K for x = 0.08. while hole concentration decreases. i.e.. iron atoms exhibit donor properties. The easy-axis for magnetization is parallel to the C-3 crystallographic axis, In n-type samples, Bi2-xFexSe3 ferromagnetic transition was not found. The de Haas-van Alphen effect was clearly observed with the frequency of oscillation decreasing with Fe doping. We observed also the jump of the resistivity at T = T-c The Seebeck coefficient alpha also has been measured at room temperature. With an increase in the content x of Fe atoms. the value of x increases from alpha = 215 muV/K in the host material p-Bi2Te3 to 260 muV/K in Bi1.92Fe0.08Te3 with maximal Fe content. (C) 2002 Elsevier Science B.V. All rights reserved.