Abstract
We study the field and temperature dependences of the magnetization (B≤7.5 T, T=2.0-75 K) of samples from a single crystal Pb1-x-ySnxVyTe (x=0.08, y=0.01) ingot synthesized by the Bridgman method. It is established that the magnetization of the samples contains two main contributions: the Brillouin-type paramagnetism of vanadium ions and the diamagnetism of the crystal lattice. Experimental field and temperature dependences of the magnetization are discussed in the framework of a theoretical model of electronic structure rearrangement in Pb1-x-ySnxVyTe with doping and approximated as the sums of two terms based on the modified Brillouin functions for vanadium ions in the V3+ and V2+ states. The concentrations of magnetically active vanadium ions in two different charge states with increasing impurity concentration along the ingot are determined.
Highlights
It is well known that doping of PbTe with vanadium leads to appearance of a deep impurity level EV under the bottom of the conduction band (EV≈Ec–20 meV) [1, 2]
After filling the valence band with electrons, the Fermi level stabilizes inside the impurity band of vanadium, and the concentrations of filled and empty states in this band should become equal to the concentrations of the impurity ions in two different charge and magnetic states: V2+(3d3) and V3+(3d2), respectively
The analysis of these dependences allow us to conclude that, in contrast to the previously investigated alloys Pb1-yFeyTe [9], in which the impurity level lies in the valence band, the magnetization of Pb1-x-ySnxVyTe alloys contains only two main contributions
Summary
It is well known that doping of PbTe with vanadium leads to appearance of a deep impurity level EV under the bottom of the conduction band (EV≈Ec–20 meV) [1, 2]. After filling the valence band with electrons, the Fermi level stabilizes inside the impurity band of vanadium, and the concentrations of filled and empty states in this band should become equal to the concentrations of the impurity ions in two different charge and magnetic states: V2+(3d3) and V3+(3d2), respectively. The magnetic properties of diluted magnetic semiconductors Pb1-x-ySnxVyTe should be determined by the impurity concentration, and by the ratio of the concentrations of vanadium ions in two different magnetic states. Our main goals are to determine the kinetics of changes in concentration of magnetic ions in two different magnetic states along the ingot and to establish a correlation between the magnetic and galvanomagnetic properties of alloys in the framework of the model of rearrangement of the electronic structure of Pb1-x-ySnxVyTe upon doping
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