In this work we studied variation of structural and microstructural features of Cd3As2 3 As 2 compound upon introducing the Cr component. Obtained X-ray diffraction data suggest that parent Cd3As2 3 As 2 phase in studied polycrystals conserve both symmetry and volume of the unit crystal cell, implying low solubility limit of Cr (well below 1 at.%). % ). Instead, addition of Cr results in the appearance of CrAs and pure Cd phases. The latter is detected in the form of inclusions of Cd-Cd3As2 3 As 2 eutectic. Obtained data reveal that CrAs phase formation have rather specific mechanism related to As diffusion, as for large Cr-containing regions we observed clear gradient of As and Cr concentration with radial symmetry. Therefore, varying synthesis parameters one may obtain core-shell inclusions containing different Cr-As phases. Combination of results of thermal and microstructural analysis suggests that Cd3As2 3 As 2 and CrAs phases are immiscible.

The article presents a review of research focused on the synthesis, crystalline and band structures, magnetic and electrophysical properties, and applications of the soft magnetic ferromagnet MnSb, which is characterized by a high Curie temperature. In analyzing the presented data, the authors adhered to the core concept of physicochemical analysis of the composition–structure–properties relationship.

Composite Films (Сd3As2)100-X(MnAs)X on silicon and sitall substrates with a concentration of Mn 5.8-16.4 at.% were obtained by vacuum-thermal evaporation. The structural properties of the films were investigated by X-ray phase analysis and scanning electron microscopy. Magneto-optical properties were studied by the method of the equatorial Kerr e ect (EEC) in the energy range of 0.5-4.0 eV in magnetic elds with a strength of up to 3 kE at a temperature of 20-300 K. In the geometry of the equatorial Kerr effect, spectral, field and temperature dependences of the EEC are obtained. The analysis of experimental data showed that with a Mn content of more than 12.9 at.% of the films contain the α′′-phase of the topological Dirac semimetal Cd3As2 in the form of large granules, as well as ferromagnetic MNAs granules. The Curie temperature of lms depends on the Mn content in them and is less than the temperature of bulk samples ofMPas. When the Mp content in the lm is 5.8 at.% and 6.4 at.%, the magneto-optical response is not detected, which indicates the formation of a superparamagnetic state or a spin glass state at low concentrations of Mn. With a film content of Mn 9.9 at%. A signi cant change in magneto-optical spectra was detected, which indicates the formation of MNAs nanoclusters and partial dissolution of Mn in the Cd3As2 matrix.

Composite films of (Cd _3 As _2 ) _100-X (MnAs) _X on silicon and sitall substrates with Mn concentration of 5.8–16.4 at % were obtained by vacuum-thermal evaporation. The structural properties of the films were investigated by X-ray phase analysis and scanning electron microscopy. Magneto-optical properties were studied using the transverse Kerr effect (TKE) method in the energy range of 0.5–4.0 eV in magnetic fields up to 3 kOe at temperatures of 20–300 K. In the geometry of the transverse Kerr effect, the spectral, field, and temperature dependences of TKE were obtained. Analysis of experimental data showed that at Mn contents more than 12.9 at % the films contain the α^'' -phase of the topological Dirac semimetal Cd _3 As _2 in the form of large granules, as well as ferromagnetic MnAs granules. The Curie temperature of the films depends on their Mn content and is lower than that of bulk MnAs samples. At Mn contents in the film of 5.8 and 6.4 at % , no magneto-optical response was detected, indicating the formation of a superparamagnetic state or a spin glass state at low Mn concentrations. At an Mn content in the film of 9.9 at % , a significant change in magneto-optical spectra was observed, indicating the formation of MnAs nanoclusters and partial dissolution of Mn in the Cd _3 As _2 matrix.

Contributions from constants K1 and K2 of first- and second-order magnetic anisotropy to the effective constant are separated. Their competition determines the type of easy-plane magnetic anisotropy. Extrapolating dependences K1(T) and K2(T) to the region of high temperatures allows the prediction of temperature TSR = 570 K of the spin-reorientation transition, during which easy-axis magnetic anisotropy is formed.

Two types of Cd 3 As 2 -MnAs composite films were synthesized by vacuum-thermal evaporation technique on substrates held at 300 and 427 K. According to X-ray diffraction data, studied films contained alpha ''-Cd 3 As 2 (P4 2 / nmc) and MnAs (P6 3 /mmc) crystalline phases, traces of the amorphous phase were also detected. Stabilization of the metastable alpha ''-phase suggested the formation of (Cd 0.92 Mn 0.08 ) 3 As 2 ternary compound crystallites in studied films. The average crystallite size is higher for films obtained at higher substrate temperatures (427 K). However, the results of Magnetic Force Microscopy (MFM) studies suggested that the spatial distribution of relevant phases is more homogeneous in films deposited at lower substrate temperatures (300 K). According to the results of MFM studies and electromagnetic measurements, films under study demonstrate ferromagnetic properties and metallic-type conductivity. The films were characterized by negative magnetoresistance, the amplitude of which depended on the substrate temperature and saturated around 0.14 T (1.4 kOe) with maximum value of 5.35 % observed for the film obtained at 300 K. The presence of negative magnetoresistance in studied films suggested the appearance of carrier spin polarization. The linear character of the temperature dependence of resistivity of studied films makes them promising for applications as temperature and magnetic field sensors.

In this work we studied variation of structural and microstructural features of Cd3As2 compound upon introducing the Cr component. Obtained X-ray diffraction data suggest that parent Cd3As2 phase in studied polycrystals conserve both symmetry and volume of the unit crystal cell, implying low solubility limit of Cr (well below 1 at.%). Instead, addition of Cr results in the appearance of CrAs and pure Cd phases. The latter is detected in the form of inclusions of Cd–Cd3As2 eutectic. Obtained data reveal that CrAs phase formation have rather specific mechanism related to As diffusion, as for large Cr-containing regions we observed clear gradient of As and Cr concentration with radial symmetry. Therefore, varying synthesis parameters one may obtain core–shell inclusions containing different Cr–As phases. Combination of results of thermal and microstructural analysis suggests that Cd3As2 and CrAs phases are immiscible.

— A composite consisting of 80 mol % α''-Cd 2.76 Mn 0.24 As 2 and 20 mol % MnAs has been synthesized and characterized by X-ray diffraction, differential thermal analysis, and microstructural analysis. The results demonstrate that the composite is a soft ferromagnetic material with a Curie temperature of 328 K. In the temperature range 4–300 K, its electrical conductivity shows metallic behavior. The composite has a high positive magnetoresistance, up to 600% in a magnetic field of 8 T. The nature of its magnetoresistance is determined by the Lorentz force, which suppresses the effect of the spin magnetic moments of the MnAs ferromagnet. Owing to the linear behavior of the temperature and magnetic field dependences of its electrical resistance, the composite is of practical interest for use as a material for temperature and magnetic field sensors.

A composite consisting of 80 mol

In this work we report the results of complex studies of basic properties and phase equilibria in GaSb-GaMn system within wide composition range. Investigated alloys were synthesized using regimes with relatively low crystallization speed, which resulted in a formation of stable monoclinic modification of GaMn, as suggested by the X-ray diffraction data analysis. The latter also suggested the negligible role of mutual solubility of components in agreement with spatial distribution of elements in studied alloys determined using energy dispersive X-ray spectroscopy. Combination of microstructural data and results of differential thermal analysis reveals the eutectic character of interaction in GaSb-GaMn system with eutectic composition corresponding to 45 mol.% of GaMn and melting temperature of 609 degrees C. This temperature is substantially lower than reported values of peritectic melting temperature of GaMn, which suggests the possibility of stabilizing hard ferromagnetic L10-GaMn modification in GaSb-GaMn system without substantial deterioration of crystal quality typical for GaMn compounds.

Resistivity ρ, magnetoresistance Δρxx/ρ0(P) and Hall constant RH were measured in (Cd1 – xZnx)3As2 sample with х = 0.31 under the action of all-round pressure and at various temperatures in the range (80–400) K. These samples were obtained by the modified Bridgman method. The composition of the samples and their homogeneity were controlled by X-ray phase analysis and energy-dispersive X-ray spectroscopy. The results of energy dispersive X-ray spectroscopy showed that the distribution of elements in the sample is uniform. It was found that the resistivity increases with increasing temperature, and the change in ρ(T) has a metallic character. The Hall constant RH in the field decreases slightly with increasing temperature and retains a negative sign throughout the entire range under study. With increasing pressure, anomalies were observed in the baric dependences of the electrical resistivity ρ(Р), magnetoresistance Δρxx/ρ0(Р) and the Hall coefficient RH(Р). Increasing the confining pressure leads to suppression of the positive magnetoresistance. In the phase transition region, the negative magnetoresistance at a pressure Р (2.4–2.7) GPa in a field of 5 kOe is the maximum value of 1.7.

The resistivity ρ, magnetoresistance Δρ xx /ρ 0 ( P ), and Hall coefficient R H are measured in a (Cd 1 ‒ x Zn x ) 3 As 2 sample with х = 0.31 under the action of uniform pressure and at various temperatures in the range 80–400 K. These samples are obtained by the modified Bridgman method. The composition of the samples and their homogeneity are controlled by X-ray phase analysis and energy-dispersive X-ray spectroscopy. The results of energy dispersive X-ray spectroscopy show that the distribution of elements in the sample is uniform. It is found that the resistivity increases with increasing temperature, and the change in ρ( T ) has a metallic character. The Hall coefficient R H in the field decreases slightly with increasing temperature and retains a negative sign throughout the entire range under study. With increasing pressure, anomalies are observed in the baric dependences of the electrical resistivity ρ( Р ), magnetoresistance Δρ xx /ρ 0 ( Р ), and the Hall coefficient R H ( Р ). Increasing the uniform pressure leads to suppression of the positive magnetoresistance. In the phase-transition region, the negative magnetoresistance at a pressure of Р (2.4–2.7) GPa in a field of 5 kOe is a maximum value of 1.7.

The results of experimental studies of the resistivity, Hall effect, and magnetoresistance of Cd3As2 + kMnAs composites (k = 20, 30, 44.7 mol

In this work, we studied properties of the GaSb-MnSb composite (30 mol.% GaSb + 70 mol.% MnSb), synthesized from a melt of elemental precursors and subjected to the post-growth quenching procedure. We used a combination of experimental methods to specify phase composition of studied systems and elemental composition of each phase. Presented results suggest that studied composites can be considered as an ensemble of large ferromagnetic MnSb inclusions (with sizes of order of 10 mu m) embedded in GaSb matrix with small amount of diluted Mn atoms in it. We show that magnetic and magnetooptical properties of composites are primarily defined by the MnSb phase. However, transport and magnetotransport properties of GaSb-MnSb samples depends on both components. In general, low temperature magnetotransport is dominated by the contribution of the GaSb matrix, while at room temperature measured data are qualitatively similar to those for pristine MnSb polycrystals. Additive character of these contributions along with the absence of any magnetooptical response besides that characteristic for bulk MnSb polycrystals suggests that these composites do not contain any considerable fraction of nm-sized ferromagnetic inclusions. Nevertheless, our results suggests that bulk GaSb-MnSb nanocomposite can be obtained, e.g. by more aggressive quenching.

Considerable interest to magnetism of MnAs both in bulk or in the form of epitaxial films is stimulated by its applications as a magnetocaloric material and in spintronic devices. Since the MnAs films deposited on GaAs reproduce well a magnetic transformation related to α–β magnetostructural transition that occurs in bulk MnAs, this first-order phase transition occurs through a phase coexistence over a wide temperature range. Here, we considered the same magnetostructural transition in a bulk hybrid structure based on micrometer-scaled MnAs inclusions embedded into the Cd3As2 matrix. In particular, the effect of high pressure and magnetic fields on the ferromagnetic transition temperature, TC, in a composite Cd3As2 + 30 mol. % MnAs has been studied. We found that at ambient pressure, the transition from α-MnAs to β-MnAs is accompanied by the absence of thermal hysteresis of magnetization, implying a phase coexistence regime. The hysteresis width does not markedly increase even at pressures about P = 0.35 GPa, and displacement of TC occurs with a rate of dTC/dP ∼ −91.42 K/GPa. In the temperature region of the α–β phase coexistence, a local peak at T = 283 K and P = 1 GPa is observed, which is associated with an antiferromagnetic order of MnAs inclusions. Direct measurements of isothermal magnetization vs pressure indicate both the stabilization of the ferromagnetic hexagonal α phase at P < Pmax and the development of an orthorhombic antiferromagnetic long-range order, which propagate up to 5 GPa.

Cd-Mn-As ternary system triangulation was carried out. Cd3As2−MnAs, MnAs-CdAs2 and Cd3As2−CdAs2 cross-sections as quasi-binary systems were chosen, which create the Cd3As2−MnAs-CdAs2 ternary system. By physical-chemical analysis XDA, DTA and by the microstructures investigation it was shown that this ternary system is characterized by the presence of three double eutectics, which form a ternary eutectic. The coordinates for eutectics are: 70 mol. % Cd3As2 & 30 mol. % MnAs, Tm.ev = 708 °C; 94 mol. % CdAs2 & 6 mol. % MnAs, Tm.ev = 614 °C; 56 mol% Cd3As2 & 44 mol% CdAs2, Tm.ev = 610 °C and for ternary eutectic is 8.4 % Cd3As2 & 5 mol. % MnAs, 86.6 % CdAs2, Tm.ev = 600 °C. Based on such data, liquidus isotherms for the Cd3As2−MnAs-CdAs2 system were constructed. This system alloys were soft ferromagnets with Tc ∼ 318 K, in which the magnetization increased with an the MnAs content rise. Such ferromagnets can be interesting as materials for creating microcoolers based on the magnetocaloric effect and for spintronic devices based on magnetogranular structures consisting of a semiconductor matrix and MnAs nanoclusters.

The Cd–As system is distinguished by metastable states; three compounds, namely, Cd3As2, CdAs2, and CdAs4, are formed in the system under normal pressures. The last-listed compound, CdAs4, is metastable and can be prepared, as a rule, together with other phases that stabilize it, e.g., with isostructural CdP4. The focus of research is Cd3As2. This compound was first regarded as a narrow-gap semiconductor with an abnormally high electron mobility. More recently, Cd3As2 has been rediscovered as a 3D topological semimetal, positioned as a bulk analogue of graphene that has a negative magnetoresistance (NMR) and superconductivity. The conduction band and valence band of cadmium arsenide have a linear dispersion law and touch each other in the 3D Brillouin zone to form Dirac points. Provided the time reversal and inverted symmetry, the Dirac points are doubly degenerate. Symmetry breaking leads to splitting of a Dirac point. A magnetic field transforms the Weyl semimetal, generating NMR and giving rise to superconducting properties. The second stable compound of the three listed, CdAs2, is a semiconductor with a moderate bandgap width, and is distinguished by a high anisotropy of optical, electrical, and thermoelectrical properties. This compound is interesting due to the high value of birefringence in the IR. The review analyzes the synthetic methods to prepare single crystals and thin films. Data are presented on thermodynamic properties, the effects of doping with donor and acceptor dopants, types of defects, and their relations to optical and electrical properties. Present-day studies are reviewed.

In this article, we report research data for the isothermal magnetization of a composite consisting of Cd3As2 Dirac semimetal and MnAs ferromagnet (30 mol %) at pressures up to 5 GPa. A magnetic transformation in MnAs inclusions, the size of which presumably varies from a micro- to nanoscale, has been found to be similar to that in bulk MnAs compound, except for a hysteresis in the range of magnetostructural transformation. Under hydrostatic pressure, a magnetization maximum has been revealed at pressures P ≥ 0.77 GPa, which is indicative of ferromagnetic ordering improvement. The conclusion has been drawn that that the above features are due to the superparamagnetic nature of nanometer-sized MnAs inclusions in the Cd3As2 matrix.

The results of studying the thermal emf of composites Cd3As2 + n mol % MnAs (n = 10, 20, 30, 44.7) at high pressures up to 50 GPa are presented. In the pressure ranges of P = 28–35 GPa (n = 10, 20), 20–35 GPa (n = 30), and 30–35 GPa (n = 44.7), all the materials studied exhibit specific features in the behavior of the thermal emf S(P) (extrema, inflection points on the curves or hysteresis). At a pressure exceeding 40 GPa, the thermal emf changes weakly or barely changes with an increase and a subsequent decrease in pressure.