Crystallization-induced semiconductor-metal transition in an amorphous CoFeTaBO magnetic semiconductor nanocomposite

In the present study, we investigated the effects of crystallization on magnetic and electrical properties of an amorphous CoFeTaBO magnetic semiconductor nanocomposite. Crystallization was found to trigger a semiconductor-metal transition in the nanocomposite. The room-temperature resistivity was decreased by nearly three orders of magnitude due to the crystallization. The crystalline phase in the sample was determined to have CoFe2O4-type cubic spinel structure. In comparison with the amorphous nanocomposite, the crystallized nanocomposite exhibited much harder ferromagnetism. The out-of-plane coercivity of the as-prepared sample was increased from below 1 Oe to ∼490 Oe. In addition, the crystallized sample exhibited enhanced anisotropic magnetoresistance. The crystallization-induced significant difference in the magnetic and electrical properties may enable the amorphous nanocomposite as a magnetic phase change material to play an important role in magnetoelectric devices. •A semiconductor-metal transition is induced by crystallization of a nanocomposite.•The resistivity of the sample decreases by nearly three orders of magnitude.•The out-of-plane coercivity was increased from below 1 Oe to ∼490 Oe.•The crystallized sample exhibited enhanced anisotropic magnetoresistance.