Native vacancy defects in Zn1-x(Mn,Co)xGeAs2 studied with positron annihilation spectroscopy

We have studied vacancy defects in chalcopyrite semimagnetic semiconducting mixed Zn1−x(Mn,Co)xGeAs2 bulk crystals with alloy composition x varying between 0.052 to 0.182 using positron annihilation spectroscopy. We identified As vacancies, potentially complexed with the transition metal alloying elements, in all the studied samples, while no cation vacancy related defects were detected. The positron lifetimes for the bulk ZnGeAs2 lattice and neutral As vacancy were determined to be τB=220–230 ps and τAs=300±10 ps, respectively. Our results also show that the p-type conductivity in the samples is not due to cation vacancy related acceptor centers. The As vacancies were found to be present at such low concentrations that they cannot be responsible for the compensation of the p-type conductivity or the reduction of mobility in the Zn1−x(Mn,Co)xGeAs2 samples.Peer reviewe

Point defects and p-type conductivity in Zn1-xMnxGeAs2

Positron annihilation spectroscopy is used to study point defects in Zn1–xMnxGeAs2 crystals with low Mn content 0≤x≤0.042 with disordered zincblende and chalcopyrite structure. The role of negatively charged vacancies and non-open-volume defects is discussed with respect to the high p-type conductivity with carrier concentration 10exp19≤p≤10exp21cm−3 in our samples. Neutral As vacancies, together with negatively charged Zn vacancies and non-open-volume defects with concentrations around 10exp16−10exp18 cm−3, are observed to increase with increasing Mn content in the alloy. The observed concentrations of defects are not sufficient to be responsible for the strong p-type conductivity of our crystals. Therefore, we suggest that other types of defects, such as extended defects, have a strong influence on the conductivity of Zn1–xMnxGeAs2 crystals.Peer reviewe

Pressure and temperature dependences in p-ZnAs2 at high pressures

Kinetic effects in p-ZnAs2 were measured at hydrostatic (P ≤ 9 GPa) and quasi-hydrostatic (to P ≤ 50 GPa) pressures on pressure buildup and depressurization. A conclusion on the occurrence of two phase transitions was made: I-II at P = 9-15 GPa and II-III at P = 30-35 GPa. Based on the temperature dependences of electrical resistance, it was shown that the conductivity is determined by activation mechanisms in a temperature range of 250-400 K; in this case, the activation energy changed with temperature and pressure. The pressure dependences of the activation energy and the coefficient R 0, which characterizes the mobility, concentration, and effective mass of carriers, were calculated. © 2013 Pleiades Publishing, Ltd

The synthesis and investigation of the electrical properties of tricadmium diarsenide with MnAs nanogranules

Samples of tricadmium diarsenide with MnAs nanogranules (44.7 mol % MnAs) are synthesized. The morphology of the samples is studied by X-ray phase analysis and electron microscopy. The electrical properties of tricadmium diarsenide with MnAs nanogranules are studied in a range of temperatures of 77-372 K.

Spin-Polarized Electric Current in Cd48.6Mn11.4As40 Nanocomposite

Abstract: For the first time, the temperature dependences of the electrical resistivity and magnetization of the Cd48.6Mn11.4As40 nanocomposite were measured in the temperature range of 10–350 K. It is shown that the electrical properties of Cd48.6Mn11.4As40 are associated with spin polarization of intrinsic electrons in the Cd3As2 matrix by spin-polarized electrons injected into it from ferromagnetic MnAs nanoclusters. With an increase in the magnetization of the entire sample, the angle between the magnetization directions of individual nanoclusters decreases and the spin-polarized current increases. Furthermore, an increase in the concentration of intrinsic carriers in the matrix leads to an increase in the spin-polarized current. This concept is also confirmed by measurements of current–voltage characteristics (CVCs) at voltages of up to 5 V at temperatures both below critical temperature Tcg = 241 K of cluster glass formation (at 77 and 172 K) and above it (at 273.15 and 373.15 K), which exhibit an increasing deviation from the ohmic behavior with an increase in the stress. This means that the greater the spin polarization of intrinsic electrons in Cd3As2 due to an increase in the injection of spin-polarized electrons from MnAs with an increase in the voltage, the higher the current. © 2021, Pleiades Publishing, Ltd