Thermoelectric power and Hall effect were measured for Pb 1−x −y Sn y Mn x Te samples with 0.00 ≤ x ≤ 0.12 and 0.72 ≤ y ≤ 0.80, with carrier concentration 1.9 × 10 20 ≤ p ≤ 2.5 × 10 21 cm −3 over a temperature range T = 4.2-300 K. The analysis of the experimental data based on a two-valence-band model was performed. The theoretical description of the light holes of the L band is based on the Dimmock model. For heavy holes from the band the parabolic dispersion relation was assumed. Our analysis indicates that with increasing Mn content the energy gap (E g ) increases: ∂E g /∂x = 25 meV at.% −1 , whereas the energy separation between the bands of light and heavy holes (E ) decreases: ∂E /∂x = −12 meV at.% −1 . We also observe an increase of the effective mass of heavy holes (m ) from m = (1.0 ± 0.25)m 0 for samples with x ≤ 0.09 to m = 2.1m 0 for x = 0.12.
The physical properties of ferromagnetic dilute magnetic semiconductors and nanocomposites are considered in a wide range of temperatures from 5 to 300 K. The latter have several advantages as spintronic materials with a controlled magnetic structure for weak magnetic field sensors. A characteristic feature of ferromagnetic nanocomposites is the spin-dependent tunneling conductance, which is responsible for the negative and positive magnetoresistance. The magnetoresistive effects have a wide range of applications. In particular, materials with such effects may be used in the development of magnetoresistive memory devices, weak magnetic field sensors, medical diagnostic devices, and other items of electronic equipment.
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