Giant negative magnetoresistance in a nonmagnetic semiconductor
Henriques A.B., Obukhov S.A., Oliveira N.F.Yr., Sanina V.A.
PACS: 71.30.+h, 71.45.Gm, 72.15.Eb, 72.80.Ga
Studies of a classical ASB5 semiconductor (InSb) doped with 3d magnetic ions (Mn2+, having a localized spin 5 = 5/2) 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 ìçÍÐ ~ Ncr = 2 ž 101T cm-3 and a temperature Τ < Tcr ~ ~ 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 Nt/in ~ Ncr-A model describing the gap formation is proposed.