Magnetic properties of Pb1-xGexTe alloys doped with ytterbium

We investigate the temperature and the magnetic field dependences of magnetic susceptibility of Pb 1 - x Ge x Te(0≤x≤0.1) alloys doped with Yb (C Y b ≤3.6 mol.%). The obtained magnetic susceptibility of the alloys is formedof two shares: diamagnetic, prevailing at the room temperature, and the Curie-Weiss paramagnetic, dominating at low temperatures. From the values of the Curie constant, the concentration of magnetically active centers is estimated. We have found that the fraction of the magnetic centers increases with the increase of the Yb content, but is significantly lower than the total Yb concentration in the investigated alloys. The obtained results are explained taking into account existing of magnetic Yb 3 + and nonmagnetic Yb 2 + ions in the alloys and the possibility of transition of ions from one state to the other due to shift of the Yb impurity level with respect to the valence band edge as the composition of the alloy changes.