Pb1−x\text{}_{1-x}Mnx\text{}_{x}Te Crystals as a New Thermoelectric Material

We studied experimentally thermoelectric properties of p-type bulk crystals of Pb$\text{}_{1-x}$Mn$\text{}_{x}$Te and Pb$\text{}_{1-x-y}$Ag$\text{}_{y}$Mn$\text{}_{x}$Te (0≤ x≤ 0.083 and y≤0.017) at room and liquid nitrogen temperatures. Model calculations of the thermoelectric figure of merit parameter (Z) involved the analysis of carrier concentration, carrier mobility, density of states as well as electronic and lattice contributions to the thermal conductivity of PbMnTe. In the analysis we took into account the main effect of Mn concentration on the band structure parameters of PbMnTe, i.e. the increase of the energy gap. The analysis of electrical, thermoelectric, and thermal properties of Pb$\text{}_{1-x}$Mn$\text{}_{x}$Te crystals showed that, at room temperature, the maximum values of the parameter Z occur in crystals with Mn content 0.05≤ x≤0.07 and are comparable with a maximal value of Z observed in PbTe. At T=400 K the increase in the parameter Z by 10% is expected in Pb$\text{}_{1-x}$Mn$\text{}_{x}$Te crystal (as compared to PbTe) for a very high concentration of holes of about p=5×10$\text{}^{19}$ cm$\text{}^{-3}$. The experimental data correctly reproduce the theoretical Z(p) dependence

Magnetic Anisotropy in Geometrically Frustrated Kagome Staircase Lattices

This paper reviews experimental results concerning magnetic anisotropy in geometrically frustrated kagome staircase lattices. Following problems are discussed: high-temperature susceptibility measurements of kagome single crystals; inelastic neutron scattering measurements on Co3V2O8 single crystals; EPR of Co2+ ions in kagome staircase Mg3V2O8 single crystals. The single-ion anisotropy Hamiltonian is used to analyze experimental results. It is suggested that the magnetic anisotropy in kagome staircase M3V2O8 (M \ubc Co, Ni, Mn) oxides has mainly single-ion origin.Peer reviewed: YesNRC publication: Ye

(Eu,Gd)Te - MBE Growth and Characterization

Monocrystalline thin layers of (Eu,Gd)Te, n-type ferromagnetic semiconductor, were grown by molecular beam epitaxy technique on BaF$\text{}_{2}$ (111) substrates. Reflection high-energy electron diffraction, X-ray diffraction, and atomic force microscopy characterization proved epitaxial mode of growth and high crystal quality of the layers. Magnetic susceptibility and magnetic resonance measurements showed that in (Eu,Gd)Te layers ferromagnetic transition takes place at about 13 K. Electrical characterization carried out by the Hall effect and resistivity measurements revealed very high electron concentration of 10$\text{}^{20}$~cm$\text{}^{-3}$ and sharp maximum of resistivity at transition temperature