Giant negative magnetoresistance effect in PbTe(Yb,Mn)

We report on the observation of the giant negative magnetoresistance effect in PbTe doped simultaneously with Yb and Mn. In some impurity concentratio n range, the sample resistance at the liquid helium temperature drops by ab out three orders of magnitude when the magnetic field increases up to 5-6 T , with subsequent rise by about one order of magnitude as the field increas es to 17.5 T. The effect is observed up to T=35 K. The possible origin of t he effect is discussed.