Dynamic effects in EPR spectra of the Pb_1-xMn_xTe thermoelectric crystals

Abstract

It was shown by EPR method that increasing of an average manganese concentration in the Pb1-хMnхTe semimagnetic thermoelectric crystals (x > 0,002) leads to an non-uniform distribution of the Mn2+ ions in the body of the Pb1-хMnхTe solid solution and to formation of some microscopic regions where a content of the Mn2+ ions is rather high. In these regions, the effect of the dipolar instability associated with an displacement of the Mn2+ ions from central position to one of the 8 non-central equivalent positions of the tetragonal type is realized. Each of them corresponds to an adiabatic potential well separated from others by energy barriers. An analysis of the angular and temperature dependencies in the EPR spectra shows that the energy barriers between neighboring non-central positions are not very high and this is a reason for an impurity ion to be tunneling through the barriers with frequencies which are higher than the EPR frequency.

Keywords

• thermoelectric
• leadtelluride
• epr
• manganese
• impurity
• dipolar instability
• non-central position