The growth of both monoclinic and cubic phases for ultrathin (UT) and thin FeSi and CrSi films and only cubic phase for CoSi on silicon was proven as confirmed by HRTEM. At temperatures of 2–30 K, shunting is absent for the UT films and the two-dimensional conductivity model is realized. In the temperature range of 2–30 K and magnetic fields of 0.25–8 T for the UT films: concentrations and type of majority carriers are determined; NMR and SMR regions are observed in FeSi and CoSi films; quantum MR model is realized in CrSi films at T = 2 K. Ferromagnetic loops and a superparamagnetic phase are observed in UT m-FeSi and c-CoSi films from 3 to 300 K. Temperature dependences of the power factor and ab initio calculations of the lattice thermal conductivity of nanowires made it possible to estimate ZT for FeSi and CoSi films as a function of temperature.

In the first part [N. G. Galkin et al., Ultra-thin and thin CrSi films on Si(111): I. Formation and crystal structure, J. Mater. Chem. C, 2024 (part 1)], structural features of ultra-thin (UT) and thin CrSi films have been considered indicating that the ground state of CrSi is monoclinic but not cubic as previously believed, whereas the grown films consisted of grains with both monoclinic and cubic phases. In this part, we present the results on the transport, magnetotransport, and magnetic properties of UT and thin CrSi films. In the UT CrSi films (3.19 nm with the predominant contribution of the m-CrSi phase), quantum magnetoresistance with an extremely low magnetoresistive effect (0.025-0.10%) is observed at 2-30 K, but the ordinary and anomalous Hall effects for holes coexist in the temperature range of 40-100 K. The main carriers in the thin (about 31-47.7 nm) CrSi films, consisting of m-CrSi and c-CrSi phases, are revealed to be holes with a concentration of 2.6 x 1022 cm-3 and a mobility of 4.78-4.95 cm2 V-1 s-1. According to the conductivity simulation, 2D-like conductivity is observed for UT monoclinic CrSi films, which is switched to 3D conductivity for thin cubic CrSi films. The UT CrSi films, predominantly exhibiting a monoclinic structure, are characterized by ferromagnetic properties at 3-300 K. According to the magnetic measurements data, the out-of-plane magnetic moment of the m-CrSi film is estimated to be 3.05 mu B and 1.05 mu B at 3 and 300 K, respectively, which is in close agreement with the results from ab initio electron structure calculations. The coexistence of c-CrSi and m-CrSi in the form of grains in thin films only leads to a decrease in the saturation of out-of-plane magnetic susceptibility from 1.42 mu B (at 3 K) to 1.05 mu B (at 300 K) and in the coercive force.

This paper presents a method for preparing magnetic nanocomposite with hierarchical structure based on Na2Ti3O7 and Fe2O3 (alpha-phase). The nanocomposite was synthesized using hydrothermal technology through combined treatment of TiO2 and various amounts of FeCl3 in a highly alkaline NaOH medium. In this method, Na2Ti3O7 nanotubes and alpha-Fe2O3 nanospheres self-assemble the compositing microparticles. The combining of nanotubular Na2Ti3O7 with nanospherical alpha-Fe2O3 enhances its visible-light sensitization. The band gap decreases across increasing content of the alpha-Fe2O3 phase, up to 2.85 eV (from 3.29 eV). The nanocomposite exhibits superparamagnetic properties. Both blocking temperature and coercive force rise with increasing alpha-Fe2O3 particles content. The obtained results enhance an understanding of how to combine different nanomaterials to design functional nanocomposites.

By means of ab initio techniques with the hybrid functional we show the existence of a new phase of FeSi with the monoclinic symmetry (space group P2(1)) originated from the B20 cubic structure (space group P2(1)3) due to slight orthorhombic distortion, which is turned out to be the ground state. The monoclinic FeSi not only displays the minimum in the total energy, but it is also characterized by a phonon spectrum without imaginary frequencies and by conducting properties (contrary to semiconducting properties of cubic FeSi) with antiferromagnetic ordering and the magnetic moment of 2.3 mu(B) for each Fe atom. These findings are supported by data of X-ray diffraction and high-resolution transmission electron microscopy of ultrathin FeSi films (similar to 3nm in thickness) grown on Si(1 1 1) by solid-phase epitaxy indicating the monoclinic symmetry to fit better the film structure as compared to the cubic symmetry, as well as by resistivity versus temperature measurements within a wide temperature range (2-300 K) pointing out bad metal properties. The analysis of field and temperature dependences of the magnetic moment of ultrathin FeSi films shows the presence of a ferromagnetic-antiferromagnetic two-phase state. We also discuss how our findings of the new phase of FeSi can interpret its known experimental data on electronic, transport and optical properties without involving the metal-insulator transition and Kondo-like effects.

The possibility of forming the La0.5Ca0.5MnO3/Al2O3/Al composite by modifying the aluminum oxide matrix, previously formed by plasma electrolytic oxidation (PEO), with calcium lanthanum manganite powder was shown. The aluminum oxide matrix represented a regular system of parallel cylindrical pores with a predominant diameter d similar to 250-300 nm. According to scanning electron microscopy images of the surface and cross-section of the composite, the use of rubbing followed by annealing at 400 degrees C made it possible to firmly fix La0.5Ca0.5MnO3 particles on the surface and in the depth of the porous PEO layer. After the "rubbing + annealing" operation, the orthorhombic modification of the La0.5Ca0.5MnO3 powder was retained with a slight change in the crystal lattice parameters. The surface of the resulting composite contained 1.8 at% Ca, 2.3 at% Mn and 1.5 at% La. The formed composite exhibited weak ferromagnetism at 300 K; lowering the temperature to 3 K led to pronounced ferromagnetic ordering with a H-c value of similar to-855/649 Oe.

The temperature dependence of the magnetization of rapidly quenched amorphous Fe–Ni–Si–B alloys was studied by the magnetometry method. The Curie temperatures were determined, and the exchange interaction parameters was calculated: the constants of spin-wave stiffness and exchange stiffness, the root mean-square range of the exchange interaction. The nearest neighboring distance between transition metal atoms was estimated based on the magnetic characteristics.

“La+Mn-containing TiO2-layer/Ti” composites were formed by plasma electrolytic oxidation in silicate electrolytes with dispersed particles of lanthanum manganite of different composition. The influence of solid-state synthesis temperature on phase composition and magnetic characteristics of lanthanum manganite powder has been studied. An increase in temperature from 870 to 1300 ºС leads to an increase in the coercivity of the powders, which is associated with a change in particle stoichiometry and size. It has been established that the properties of the powder introduced into the electrolyte affect the features of plasma electrolytic formation (voltage-time responses, final voltage), thickness, morphology, and composition of coatings. The addition of powder synthesized at a higher temperature leads to a drop in the formation voltage and a halving of the thickness of the coatings, a greater incorporation of manganese and lanthanum into the composition of the coatings and pores, as well as pronounced ferromagnetism at 3 K. The preservation of magnetic properties over time (1 year) has been tested using the example of a PEO composite obtained in a silicate electrolyte with lanthanum manganite powder synthesized at 870 °C.

The temperature dependence of the magnetization of rapidly quenched amorphous Fe–Ni–Si–B alloys was studied by the magnetometry method. The Curie temperatures were determined, and the exchange interaction parameters were calculated: the constants of spin-wave stiffness and exchange stiffness, the root mean-square range of the exchange interaction. The nearest neighboring distance between transition metal atoms was estimated based on the magnetic characteristics.

The gray-colored oxygen-deficient TiO2–δ(B) nanobelts have been synthesized through a combination of the hydrothermal method followed by an ion exchange process and vacuum annealing. Electron paramagnetic resonance reveals an existence of F-centers in the form of electron-trapped oxygen vacancies within the anionic sublattice of the gray bronze TiO2 that induces its colouration. The diffuse reflectance spectroscopy showed that the formation of oxygen vacancies into TiO2(B) significantly increases its absorption intensity in both visible and near infrared ranges. The band gap of TiO2(B) with anionic defects is equal to 3.03 eV (against 3.24 eV for white TiO2(B) treated in air). Room temperature ferromagnetism associated with the defects was detected in gray TiO2–δ(B), thus indicating it belongs it to the class of dilute magnetic oxide semiconductors. It was found that in the low-temperature range (4 K), the magnetic properties of vacuum annealed TiO2(B) do not differ from those for TiO2(B) treated in air. We hope that the findings are defined here make a contribution to further progress in fabrication and manufacturing of defective TiO2-based nanomaterials for catalysis, magnetic applications, batteries, etc.

A new approach was proposed to the formation of Ti-supported film oxide structures containing lanthanum manganite. To form layered composites, we used plasma-electrolytic oxidation in a silicate electrolyte containing lanthanum manganite powder preliminarily synthesized by the solid-phase method. The formed coating with a thickness of 55 +/- 6 mu m consisted of TiO2 (rutile), LaMnO3 and La7.58(Si1.048O4)6O2 and contained 3.3 at% La and 3.7 at% Mn in the surface layer. Particles enriched in electrolyte metals (La and Mn) were found in all com-ponents of the coating, and most of them were localized in pores and cavities, including in the form of ag-glomerates with a diameter d <= 300 nm. The resulting composite exhibited ferromagnetic ordering at room temperature. When the temperature was lowered to 3 K, the material did not undergo any phase transitions leading to a change in the magnetic ordering.

The magnetic properties of nanoobjects of nonmagnetic substances based on silicon and transition metal (iron) are considered. It is found that a system of α -FeSi _2 nanorods with a mean height of 6.6 nm and lengths from 50 to 200 nm is formed by deposition of iron with 5.22 monolayers in ultrahigh vacuum on a vicinal silicon surface Si(111)-4 ^∘ followed by annealing at a temperature of 630^∘ C. Soft ferromagnetic loops with a coercive force from 90 to 180 Oe, which persist up to a temperature of 300 K, are observed in nanorods. It is found that easy magnetization axis is perpendicular to the nanorods, while the hard magnetization axis is parallel to them. This type of nanoobjects is promising for developing spintronic devices within the planar silicon technology.

Manganese-doped anatase with a nanosized morphology (as spherically shaped nanoparticles) has been synthesized under hydrothermal conditions. It has been shown that manganese is incorporated into the titanium dioxide structure to form substitutional solid solutions. At high dopant concentrations, part of the introduced manganese goes to the formation of α-MnO 2 . A significant increase in the optical activity in the visible range and a decrease in the bandgap width down to ~2.4 eV are observed for manganese-doped anatase because of the appearance of extrinsic (multivalent Mn ions) and intrinsic compensating (oxygen vacancies) defects. It has been found that manganese-doped samples are diluted magnetic semiconductors, and the magnetic characteristics increase with increasing manganese content. All manganese-containing samples demonstrate photocatalytic activity in the degradation reaction of indigo carmine when irradiated with visible light. The degree of dye degradation depends on the content of manganese in the samples and reaches >90%.

In this study, the appearance of magnetic moments and ferromagnetism in nanostructures of non-magnetic materials based on silicon and transition metals (such as iron) was considered experimentally and theoretically. An analysis of the related literature shows that for a monolayer iron coating on a vicinal silicon surface with (111) orientation after solid-phase annealing at 450–550 °C, self-ordered two-dimensional islands of α-FeSi2 displaying superparamagnetic properties are formed. We studied the transition to ferromagnetic properties in a system of α-FeSi2 nanorods (NRs) in the temperature range of 2–300 K with an increase in the iron coverage to 5.22 monolayers. The structure of the NRs was verified along with distortions in their lattice parameters due to heteroepitaxial growth. The formation of single-domain grains in α-FeSi2 NRs with a cross-section of 6.6 × 30 nm2 was confirmed by low-temperature and field studies and FORC (first-order magnetization reversal curves) diagrams. A mechanism for maintaining ferromagnetic properties is proposed. Ab initio calculations in freestanding α-FeSi2 nanowires revealed the formation of magnetic moments for some surface Fe atoms only at specific facets. The difference in the averaged magnetic moments between theory and experiments can confirm the presence of possible contributions from defects on the surface of the NRs and in the bulk of the α-FeSi2 NR crystal lattice. The formed α-FeSi2 NRs with ferromagnetic properties up to 300 K are crucial for spintronic device development within planar silicon technology.

To understand how polyethyleneimine (PEI), as a ligand, affects structure and properties of the transition metals hexacyanoferrates (HCFs) immobilized in cross-linked PEI matrix, we have synthesized Cu(II), Zn(II), and Fe(III) HCFs via successive ion-exchange reactions with metal salts and K4[FeII(CN)6] or K3[FeIII(CN)6]. The structure and properties of the obtained materials in comparison with the crystalline HCF analogs were investigated with FT-IR, Mössbauer, and UV–Vis spectroscopy. Complete reduction of Fe(III) to Fe(II) by PEI in HCF(III) was confirmed. When synthesis was performed at pH favoring binding of precursor metal ions by PEI, cyano-bridged hybrids rather than polymer—HCFs composites were formed. Although the obtained hybrids did not demonstrate sorption activity toward cesium ions, known for crystalline HCFs, they are of interest for the other applications. SQUID measurements revealed a significant difference in magnetic properties of PEI–HCFs hybrids in comparison with crystalline HCFs. Due to the Fe(III) to Fe(II) reduction in HCF ions, Cu(II) and Fe(III) HCFs(III) lost the molecular magnets properties in PEI matrix, but magnetic ordering, including ferromagnet-antiferromagnet interactions, was observed in all hybrids over the broad temperature range.

Transparent conducting materials (TCMs) provide low cost and effective solution for the modern optoelectronics. However, simultaneous high electrical conductivity and optical transparency in the near-infrared (NIR) and middle-infrared (MIR) spectral ranges remain challenging. This study proposes thin film of the semimetal calcium disilicide (CaSi2) with hR6 polymorph modification to fill this niche. Investigation of the electrical, magnetoresistance and magnetic properties shed light on its semimetal behavior. CaSi2 film grown on Si substrate demonstrates competitive electrical and optical properties from the NIR to MIR ranges compared to commonly used TCMs reaching maximum transmittance of 47% at an important telecommunication wavelength of 1550 nm in addition to the low sheet resistance of 6.6 Omega/sq, which results in high TCM figure of merit of 0.2 Omega(-1). Moreover, demonstrated for the first time partial optical transparency of the CaSi2 in the visible range could significantly heighten its applicability for Si-based optoelectronics. (c) 2022 Elsevier B.V. All rights reserved.

Manganese-doped nanostructured composites based on TiO2 were obtained by the template sol–gel method. By a set of investigation techniques, it was established that manganese doping leads to the appearance of a rutile phase, which grows with increasing manganese content. It was found that during the template sol–gel synthesis of the TiO2/Mn composite, the doping element is not only incorporated into the titanium dioxide structure, but also forms separate phases on its surface. Study of the magnetic characteristics of the obtained composites revealed ferromagnetic ordering at room temperature, while lowering the temperature leads to an increase in the coercive force and appearance of the ferromagnet/antiferromagnet type exchange interaction. A magnetic transition at about 43 K, associated with the transfer of Mn3O4 nanoparticles to the ferromagnetic state, was detected in the composites. Undoped titanium dioxide showed a high photocatalytic activity in the visible spectral range, providing 98% degree of indigo carmine degradation. Manganese doping of TiO2 microtubes inhibited the photocatalytic activity.

Oxide layers on titanium have been formed via the method of plasma electrolytic oxidation (PEO) in electrolyte–suspensions containing colloidal particles of iron and nickel hydroxides with a ratio of Fe3+/Ni2+ = 3 : 1 for 5–15 min. The average concentrations of iron, nickel, and titanium in the composition of the coatings were 6.1, 2.2, and 3.5 at %, respectively. For all the composites, the values of coercive force Hс at 300 K did not exceed 59 Oe, which can be attributed to soft magnetic materials. At 2 K, an increase of the magnetization values and a significant increase of Hc up to 496–679 Oe have been observed for all the samples. It has been hypothesized that the contribution to the magnetic behavior of the samples at room temperature is made by the bulk of coatings, whereas at helium temperature it was the contribution of microsized formations with an increased content of iron and nickel found in the pores. Increasing the duration of the PEO process up to 15 min leads to a decrease of Hс values by almost 100 Oe at 2 K, which can result from a decrease of the proportion of iron in the composition of crystallites and the appearance of spherical particles with an increased concentration of phosphorus, titanium, and oxygen in the pores. It has been established that, after long-term storage of the samples in air, the coercive force measured at 2 K decreased by almost twice, which could have been the result of the oxidation of metallic Fe+Ni-containing particles localized in open pores on the coating surface.

Understanding the magnetic correlations in amorphous alloys is the key to enhancing their high soft magnetic properties. The magnetization correlations were studied in amorphous alloy ribbons Fe-Cu-Nb-Si-B by analysis of approach to magnetic saturation within the random magnetic anisotropy model. An unusual sequence of power laws during approach of the magnetization to saturation was observed. This may indicate the transition from isotropic to anisotropic magnetic correlations as the applied field decreases.