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This paper investigates the impact of high-energy sources, namely, high-energy plasma pulses and high-energy electron beam pulses, on materials in the form of layer through separate and combined exposures. Experimental setups utilizing a Rod Plasma Injector (RPI) and an electron gun were employed for irradiation tests. The studies involved pre- and post-treatment analysis of morphology, chemical, and phase composition using scanning electron microscopy and x-ray diffraction measurements. Surface modifications under different exposure conditions were characterized, revealing that both sources induced significant alterations in surface composition and crystal structure. These interactions result in a more uniform chemical composition, reduced surface roughness, and a shift from an amorphous phase to a nanocrystalline or amorphous-nanocrystalline state. The results underscore the potential of high-energy sources for efficient surface engineering, offering opportunities for customized material surface modifications through meticulous adjustment of these generation parameters. [ABSTRACT FROM AUTHOR]

The evolution of the structural and transport properties of underdoped La 1.952 Sr 0.048 CuO 4 thin films under a compressive epitaxial strain has been studied. The films of different thicknesses d (from 26 nm to 120 nm) were deposited using an insulating target. The onset of superconductivity in the films is observed at temperatures as high as 26 K, while small residual resistance persists at low temperatures, indicating that superconductivity is inhomogeneous. The resistance measured under a perpendicular magnetic field saturates below about 0.65 K, suggesting a possible existence of nonconventional metallic state. The magnetic-field-tuned quasi-superconductor to insulator transition is observed at a magnetic field of about 32 T. [ABSTRACT FROM AUTHOR]

The oxide glass–ceramics is a promising class of solid state materials because they are using thermally stable and chemically inert glass oxide matrices. Development of such efficient glass matrices suitable for creation of glass–ceramic materials for several purposes is an important practical task. The xLi2O–yV2O5–(100 − x − y)B2O3 undoped glass and 47Li2O–2V2O5–50B2O3–1La0.3Eu0.7VO4 glass samples with crystalline nanoinclusions were synthesized and investigated using XRD, IR and UV–Vis spectroscopy and UV band-to-band excitation of luminescence. The synthesized glass samples are characterized by wide band photoluminescence emission with maximum at 570 nm and intensity increased with increase of Li2O concentration. The excitation spectra consist of three bands with maxima located at 270, 320 and 365 nm. The observed concentration dependencies of spectral distributions in the absorption and excitation spectra are explained by influence of the lithium ions on a ratio between triborate and tetraborate groups in the glass networks. The assumption is made that the observed wide band photoluminescence emission of the glass matrix can appear as a result of recombination processes between the defects in borate networks and the broken vanadate groups. The crystalline component in the doped glass samples is found to not affect the luminescence properties of the glass matrix. Intensity of narrow band photoluminescence emission of the crystalline component is up to 10 times more intense than that of the glass matrix wide band emission. The synthesized type of the glass matrices has promising characteristics for the use of developed materials in lighting devices, as it allows improving the spectral distribution of light emission towards the white light. [ABSTRACT FROM AUTHOR]

We use resistivity and current-voltage characteristics measurements to evaluate the impact of the disorder on the nature of the Berezinskii-Kosterlitz-Thouless transition in ultrathin niobium (Nb) films. The films, with thickness in the range of 3.6-8.5 nm, show the structural transition from polycrystalline to amorphous structure upon a decrease in the film thickness. We show that this transformation results in the smearing of the Berezinskii-Kosterlitz-Thouless transition, until eventually the Berezinskii-Kosterlitz-Thouless scenario breaks down due to film inhomogeneity. [ABSTRACT FROM AUTHOR]

The magnetocaloric effect has been studied in high quality single crystals of Fe7Se8 (3c type) grown by using Bridgman's method. Magnetization and magnetocaloric effect measurements have been carried out in a magnetic field up to 5 T over the temperature range from 2 to 490 K. The spin reorientation transition from the easy c-axis to the easy c-plane, proceeding in an abrupt fashion, as a first-order phase transition, has been observed near the temperature TR ≈ 125 K. The magnetization curves in the vicinity of this transition were shown to have an S-shape with a clear hysteresis. The first order metamagnetic field induced transitions have been identified above and below TR. The conventional magnetocaloric effect related to the metamagnetic transitions has been found above TR, while below TR the inverse magnetocaloric effect was clearly seen. The existence of both kinds of magnetocaloric effect is important from the point of view of large rotating field entropy change in Fe7Se8 single crystals. The refrigeration capacity associated with a second order phase transition from the ferrimagnetic to the paramagnetic state at the Néel temperature TN ≈ 450 K was found to be weaker than that appearing near TR. The giant anisotropy of the magnetocaloric effect was related to the magnetic anisotropy of Fe7Se8 crystals. The one-ion model of the magnetocaloric effect has been developed and its predictions have been compared with experimental data. [ABSTRACT FROM AUTHOR]

This article investigated the structural, transport, and magnetic properties of a series of samples in which the La(sub 0.67)Sr(sub 0.33)MnO3 (LSMO) layer thickness is fixed at eight unit cells and that of YBa2Cu3O7(YCBO) varied from one to six cells. Magnetic moment measurements present a qualitative agreement with the model.

New data on the state of Tb3+ doping ions in the EuAl3(BO3)4 single crystals have been obtained by studying the electron paramagnetic resonance spectra within the X band and optical absorption spectra at 4 K in the visible range. Additionally, the specific heat of these crystals was measured and analyzed. It has been shown that the Tb3+ ions substitute the trivalent europium ones and lower crystal symmetry. In the crystal field, the ground multiplet of Tb3+ splits in such a way that two singlets located in close proximity are the lowest energy levels. It has been shown that the temperature dependence of the linewidth can be described by the exponential function, which is characteristic of the Aminov-Orbach processes. [ABSTRACT FROM AUTHOR]

We present the studies of magnetic and electrical properties of Sn1-x-ySixMnyTe mixed crystals. The magnetic susceptibility measurements revealed the presence of two types of transitions interpreted as a paramagnet-ferromagnet transition at T < 10 K due to carrier mediated Ruderman-Kittel-Kasuya-Yosida magnetic interactions and the anomaly related to the structural transition to the rhombohedral phase at T = 75 K. The presence of a well-defined magnetic hysteresis with a square shape confirms that the ferromagnetic state present in our samples is related to the homogeneous magnetic domain structure with narrow domain energy distribution. The contents of the magnetic ions determined via magnetometric methods is lower than the Mn contents determined via the energy dispersive X-ray fluorescence spectroscopy method indicating the presence of a large fraction of Mn ions being either short range coupled into small clusters like pairs, triples, or other entities or having lower total magnetic momentum than Mn in high-spin state. The magnetic exchange constant of our samples is equal to 0.25-0.3 eV indicating an increase with respect to ternary Sn1-xMnxTe. [ABSTRACT FROM AUTHOR]

Ferromagnetic resonance (FMR) study of magnetic anisotropy is presented for thin layers of IV-VI diluted magnetic semiconductor Ge1-xMnxTe with x=0.14 grown by molecular beam epitaxy on KCl (001) substrate with a thin PbTe buffer. Analysis of the angular dependence of the FMR resonant field reveals that an easy magnetization axis is located near to the normal to the layer plane and is controlled by two crystal distortions present in these rhombohedral Ge1-xMnxTe layers: the ferroelectric distortion with the relative shift of cation and anion sub-lattices along the [111] crystal direction and the biaxial in-plane, compressive strain due to thermal mismatch. [ABSTRACT FROM AUTHOR]

The paper presents the results of a ground state study of YGa3(BO3)4 crystals doped with erbium ions. The EPR spectrum of the Er3+ ion, which replaces yttrium ions in a crystal and is located in a slightly distorted prism of six oxygen ions, is detected and decoded. The parameters of the spin Hamiltonian describing the strongly anisotropic behavior of the spectrum are determined gk = 1:269(1), g⊥ = 9:34(6), Ak = 47:7(5) MHz, A⊥ = 320(9) MHz. [ABSTRACT FROM AUTHOR]

New data on the state of Cr3+ ion impurities in a single crystal of YGa3(BO3)4 were obtained from analysis of the electron paramagnetic resonance spectra. Crystal structure, lattice parameters, and atomic position of this crystal were studied by X-ray powder diffraction method. The Cr3+ ions are found to substitute for the trivalent gallium ions. The spectra of Cr3+ ions located at three magnetically nonequivalent sites that rotated through 120°C are registered. The obtained parameters of spin Hamiltonian of the Cr3+ ions in the YGa3(BO3)4 single crystal were analyzed. Crystal structure, lattice parameters, and atomic position of this crystal are studied by X-ray powder diffraction method. [ABSTRACT FROM AUTHOR]

Phenomena occurring at the interface may significantly modify the properties of magnetic thin films. In this paper, the effect of temperature on the magnetic properties of Co(001)/MgO/Co trilayers is studied. The trilayer structure was modified by partial coverage of Co layers by Au at the Co/MgO interface. It is found that when the quantity of deposited gold is small, formation of islands at the Co/MgO interfaces takes place, which is proved by the topological surface analysis and by the x-ray reflectivity. In the investigated trilayer structure, gradual changes of the easy magnetization axis from the in-plane to the out-of-plane direction are observed during lowering the temperature from 300 to 5 K. The analysis of the ferromagnetic resonance spectra within the multiple-magnetic-layer model system indicates that the surface anisotropy provides a significant contribution to the magnetic anisotropy of complete Co(001)/MgO/Co heterostructure. [ABSTRACT FROM AUTHOR]

Oxide multilayers composed of ferromagnetic metallic layers of La[sub 0.67]Sr[sub 0.33]MnO[sub 3] (LSMO) and superconducting cuprate YBa[sub 2]Cu[sub 3]O[sub 7] (YBCO) were grown on LaAlO[sub 3] substrates by high-pressure dc sputtering. We have investigated the structural, transport, and magnetic properties of a series of samples in which the LSMO layer thickness is fixed at eight unit cells and that of YBCO varied from one to six unit cells. The superconducting transition temperature T[sub c0] determined from the resistance measurement is higher than the temperature of the onset of the diamagnetic response T[sub d0]. This result is discussed in the frames of the model proposed by E. B. Sonin and I. Felner [Phys. Rev. B. 57, R14000 (1998)] for a ferromagnetic superconductor. The model suggests the presence of the spontaneous vortex phase in the temperature interval T[sub d0]

(Hg,Cd)Te epilayers containing a dozen percent of CdTe were grown by molecular beam epitaxy technique on GaAs wafers with thick CdTe buffer layers. The X-ray diffraction method was used to determine a chemical composition of the epilayers. The scanning electron microscopy measurements in turn were performed to determine the thickness of epilayers, and both scanning electron and atomic force microscopy to evaluate structures' morphology. The selected mechanical properties of samples were studied by the nanoindentation technique. The average values and standard deviations of the nanohardness and Young's modulus were extracted from the collected loaddisplacement data. The values of both parameters were compared with those determined for bulk crystals and those known from the literature. [ABSTRACT FROM AUTHOR]

We present studies of structural, electrical, and magnetic properties of Ge1-xEuxTe bulk crystals with the chemical composition, x, changing from 0.020 to 0.025. The sample synthesis leads to the formation of EuTe clusters in all our samples. Moreover, the presence of Ge1-xEuxTe spinodal decompositions with broad range of chemical contents is observed even for the sample with x = 0.020. Spinodal decompositions show the antiferromagnetic order with the Néel temperature, TN, equal to about 11 K, close to that for EuTe. The magnetic field dependence of the magnetization, M(B), is characteristic of the presence of magnetic inclusions in the samples. [ABSTRACT FROM AUTHOR]

We present X-ray photoelectron spectroscopy studies of epitaxial layers of Sn0.95Mn0.05Te/CdTe/GaAs(001) — a ferromagnetic topological crystalline insulator. We demonstrate that by terminating the molecular beam epitaxy growth of the layer with 20 nm crystalline Te cap one can protect the layer against oxidation at ambient conditions and, after short thermal annealing in X-ray photoelectron spectroscopy chamber, obtain atomically clean (001) surface of high crystal quality, suitable for angle-resolved photoelectron spectroscopy studies of surface topological states. [ABSTRACT FROM AUTHOR]

This work reports the results of a study of Mo thin films synthesis by DC Pulsed Magnetron Sputtering method (PMS), operating at pulse main frequency of 100 kHz and modulated by the additional modulation frequency, driving in the range of 5-1000 Hz (modulated Pulse Magnetron Sputtering - mPMS). We have studied the influence of mPMS on plasma chemical reactions and mechanisms of layer growth using optical emission spectroscopy technique. Our experiment showed strong influence of mPMS method, on the morphology (scanning electron microscopy), phase composition (X-ray diffractometry) and electric properties (4-point probes method) of nanocrystalline and amorphous Mo films. From the utilitarian point of view, low value of resistivity - 43,2 μΩcm of synthesized Mo films predestines them as back contacts for thin solar cells CIGS. Our results revealed that additional modulation frequency should be considered as an important factor for optimization of films synthesis by means of PMS-based methods. [ABSTRACT FROM AUTHOR]

The thin layers of (Sn,Mn)Te solid solution were grown by molecular beam epitaxy onto (111)-oriented BaF2 substrates and characterized by scanning electron microscopy, atomic force microscopy, energy dispersive X-ray spectrometry, and X-ray diffraction methods. The epitaxial character of the growth was confirmed. All the layers exhibited a regular (fcc) structure of the rock-salt type and were (111)-oriented, their thickness was close to about 1 µm. The layers contained up to 8% of Mn. The microhardness and the Young modulus values were determined by the nanoindentation measurements. The Berkovich type of the intender was applied, the maximum applied load was equal to 1 mN. The results of measurements demonstrated a lack of the composition dependence of the Young modulus value. A slight increase of the microhardness value with an increasing Mn content in the (Sn,Mn)Te solid solution was observed. [ABSTRACT FROM AUTHOR]

A single crystal of (Pb,Cd)Te solid solution with Cd content equal to 5% was grown by self-selecting vapour growth technique and characterized by powder X-ray diffraction using the X'Pert PANalytical diffractometer and Cu Ka1 radiation. The X-ray diffraction pattern refinement demonstrated the fcc structure of the rock-salt type of investigated sample, no precipitates or other crystal phases were detected. The sample chemical composition was determined on the basis of measured lattice parameter value. Next, the Young modulus and microhardness were determined by the nanoindentation for carefully prepared, (001), (011) and (111)-oriented single crystal plates. The slight anisotropy of two parameters mentioned above has been found and compared with available literature data. [ABSTRACT FROM AUTHOR]

PbTe and its solid solution (Pb,Cd)Te containing 2% of CdTe and PbTe grown by self-selecting vapour growth technique were investigated by inelastic X-ray scattering using synchrotron radiation. The ID28 beamline at ESRF with the incident photon energy of 17794 eV and the energy resolution of 3 meV was applied for that purpose. The measurements were performed at room temperature along [001]-type high symmetry direction in the Brillouin zone. In spite of a very low energy of phonon branches they can be determined by inelastic X-ray scattering with a high accuracy. The transversal acoustic phonon dispersion obtained by inelastic X-ray scattering corresponds well to those resulting from inelastic neutron scattering measurements and ab initio calculations. Apart from expected structures corresponding to the bulk phonons an additional scattering related to the crystal surface properties was observed in the inelastic X-ray scattering spectra. The analysis performed with the use of secondary ion mass spectroscopy technique demonstrated a presence of a thin oxide layer at sample surfaces. [ABSTRACT FROM AUTHOR]

The (Pb,Cd)Te solid solution forms a metastable single crystals for a solution containing more than 1% of CdTe due to its very low solubility in PbTe. A possible presence of a phase transitions at low temperatures (like, e.g., that occurring in the (Pb,Ge)Te solid solution starting from 1% of Ge) which could influence the physical properties of (Pb,Cd)Te system was never checked. In order to verify this possibility the neutron diffraction studies were performed in the temperature range from 21 K to 39 K in the single crystal of (Pb,Cd)Te solid solution with 2.2% of CdTe grown by self-selecting vapour growth method and characterized by powder X-ray diffraction. The (Pb,Cd)Te sample was measured using the four-circle diffractometer installed at a hot neutron source (λ= 0.83 Å). The possible transition does not take place to the lowest investigated temperature and the FWHM of Bragg peaks remains fixed in all temperature range under studies. [ABSTRACT FROM AUTHOR]

Nanoindentation measurements were performed for a single PbTe crystal grown by self-selecting vapour growth method and characterized by X-ray diffraction. The microhardness and Young’s modulus were determined for a few loads applied along the [001], [011] and [111] high symmetry directions for carefully oriented, 2 mm thick crystal plates. An anisotropy of two parameters has been suggested and compared with available literature data. The present results qualitatively confirm the theoretical predictions for a rock salt type crystal (PbS). The microhardness anisotropy value is in an agreement with recently determined, relevant value for (Pb,Cd)Te solid solution. [ABSTRACT FROM AUTHOR]

Polycrystalline La1.85Sr0.15Cu1 − xNi xO4 (0 ≤ x ≤ 0.19) solid solution with the K2NiF4 structure (S.G. I4/ mmm) is a subject of structural investigation. Rietveld refinements performed for 16 samples provide a smooth linear or almost linear variation of lattice parameters, La(Sr) atomic coordinate and bond distances with Ni content. The zO(2) oxygen coordinate tends to be constant in the studied range. The present results are compared with previous data and discussed. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Gallium nitride is studied at ambient and nonambient temperatures by powder X-ray diffraction followed by Rietveld refinement of the structure. The structure is reported for the ambient temperature on the basis of laboratory data. The diffraction data collected using a synchrotron beam serve for derivation of the lattice parameter and thermal expansion dependencies on temperature. The variation of unit-cell size on temperature was studied in detail in a broad range 11 K < T < 1073 K. The obtained dependencies of a, c and V and thermal expansion coefficients are smooth, and the results are consistent with previously collected data. The c/ a ratio shows an almost linear decreasing trend with rising temperature. The magnitude of thermal expansion obtained in the described experiments is similar to a recently reported theoretical one. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Unit cell dimensions of high-quality MnTe crystals with NiAs structure were analyzed at temperatures ranging from 295 K to 1200 K. First, the X-ray diffraction were carried out on powdered sample at room temperature using the laboratory diffractometer. Next, the diffraction patterns in a wide temperature range were accumulated with the use of synchrotron radiation. The Rietveld refinement to all experimental data was applied. The average values of linear expansion coefficients in a and c direction are reported. The observed presence of MnTe2 impurity phase in the temperature range from about 500 K to 1050 K is attributed to decomposition of a small fraction of MnTe during heating. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]