Abstract
Studies of a classical III–V semiconductor (InSb) doped with 3d magnetic ions (Mn2+, having a localized spin S=55/2) reveal some unexpected transport properties. It is found that the transition from the metallic to the low-temperature insulator phase occurs at an impurity concentration N Mn∼N cr=2× 1017 cm−3 and a temperature T<T cr∼1 K. Under these conditions a giant negative magnetoresistance arises. The experimental results can be explained in terms of the onset of a hard Mott-Hubbard gap Δ in the impurity band formed by the shallow manganese acceptor in InSb at N Mn∼N cr. A model describing the gap formation is proposed.
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Pis’ma Zh. Éksp. Teor. Fiz. 69, No. 5, 358–362 (10 March 1999)
Published in English in the original Russian journal. Edited by Steve Torstveit.