Results 1 - 10 of 697
Results 1 - 10 of 697. Search took: 0.023 seconds
|Sort by: date | relevance|
[en] Abstract—A technique of measuring the rotation of the light polarization plane in pulsed magnetic fields with strength up to 40 T with a sensitivity of 0.1° is proposed. The Faraday effect has been studied in films of diluted ferrites—garnets (Lu,Bi)3(Fe,Ga,Al)5O12 in the temperature range from room temperature to 78 K, including the vicinity of the magnetic moment compensation temperature. The transition to the noncollinear phase in the magnetic phase diagram is shown to occur at a magnetic field strength higher than 30 T at room temperature, and the threshold transition field tends to zero when approaching the magnetic moment compensation temperature.
[en] Abstract—A possibility of changing the magnetic type structure of multilayer CoPt films under action of the magnetic field of the atomic force microscope probe is demonstrated. A new method of non-contact magnetic-force measurements based on artificial increase in the electrostatic interaction between the probe and the film is proposed. This method enables one to controllably change the distance between a probe and a film, thus changing the strength of the magnetic interaction. Using it, one can create from a uniformly magnetized state both a labyrinth domain structure and isolated domains, which are apparently magnetic skyrmions.
[en] Abstract—The effect of laser pulse energy E on the possibility of forming of a homogeneous “high-temperature” ferromagnetic phase in MnxSi1 – x (x ≈ 0.5) alloy films grown by pulsed laser deposition onto an Al2O3 (0001) substrate has been studied. The high-temperature phase with manganese concentration x ≈ 0.53 and the Curie temperature TC ~ 200–300 K is shown to form near the substrate at the initial stage of the film growth. In this case, high values E ≥ 6.8 J/cm2 favor the stabilization of this phase over all film thickness, while low values E = 2.6–5.7 J/cm2 lead to a decrease in the manganese concentration in the upper film layer and the formation of additional “low–temperature” phase with TC ≈ 30–50 K provided by silicides MnSi and Mn4Si7 crystallites.
[en] The transmission spectra of GaSe and GaS crystals of different thicknesses prepared by mechanical stratification of bulk crystals have been investigated. The quantum-size shifts of exciton resonances in thin GaSe samples are as high as 12 meV, which is close to the exciton binding energy. The high-energy interband transitions in GaSe and GaS are observed near 3.4 and 3.7 eV, respectively.
[en] Specific features of the angular distributions of accelerated neutral nitrogen atoms at the grazing angles of incidence on the Al(001) crystal surface have been investigated by the computer simulation method. The N–Al pair interaction potential is approximated by the three-parameter Morse potential with the energy dependent coefficients. The angular distributions of scattered atoms have been simulated taking into account the interaction between atoms and several atomic layers in the lattice and the atomic displacement during thermal oscillations. The parameters of the pair potential of accelerated neutral nitrogen atoms in the energy range from 10 to 70 keV have been determined according to the best agreement between the calculated dependence of the rainbow scattering angle on the energy of particles incident on the crystal surface and the available experimental data.
[en] Structural parameters and IR spectra of hydrates of lithium and sodium perchlorates, calcium sulfate hydrate (gypsum), and lithium nitrate hydrate are calculated ab initio using the density functional theory. The bond lengths in the water molecules are established as functions of length and energy of hydrogen bonds. The relationship between lengths of intra-anionic and hydrogen bonds is considered. The splitting of intramolecular vibrations of water is highlighted. The stretching vibration frequency of water is determined as a function of length and energy of hydrogen bonds. The combined (mixed) vibrations of anions and molecules of water with frequencies below 1400 cm–1 are feasible as well.
[en] The magnetic and magnetodielectric properties of Ho0.5Nd0.5Fe3(BO3)4 ferroborate with the competing Ho–Fe and Nd–Fe exchange couplings have been experimentally and theoretically investigated. Step anomalies in the magnetization curves at the spin-reorientation transition induced by the magnetic field B ║ c have been found. The spontaneous spin-reorientation transition temperature TSR ≈ 8 K has been refined. The measured magnetic properties and observed features are interpreted using a single theoretical approach based on the molecular field approximation and calculations within the crystal field model of the rare-earth ion. Interpretation of the experimental data includes determination of the crystal field parameters for Ho3+ and Nd3+ ions in Ho0.5Nd0.5Fe3(BO3)4 and parameters of the Ho–Fe and Nd–Fe exchange couplings.
[en] Using the Monte Carlo method, magnetic structures of the ground state and thermodynamic properties of the antiferromagnetic Ising model on a body-centered cubic lattice with competing exchange interactions are studied. The investigations are carried out for the ratio of the exchange interactions of next and nearest neighbors r = J2/J1 = 2/3. All possible magnetic structures of the ground state for this ratio of exchange interactions have been obtained. It has been shown that at r = 2/3 the competition of exchange interactions does not lead to the appearance of frustration and degeneracy of the ground state. Based on the histogram data analysis, it has been shown that the phase transition of the second kind is observed in the model under study at r = 2/3.
[en] A comparative analysis of the magnetic properties and Mössbauer spectra of two Ce2Fe17 samples prepared by different methods and demonstrating different magnetic behavior is carried out. A model for processing the spectra is proposed, which gives a good description of the Mössbauer spectra of samples in different magnetic states by a superposition of eight subspectra. It is shown that in the samples in the ferromagnetic state there are regions with antiferromagnetic ordering at the local level. The relative fractions of iron atoms in these regions differs for different samples and increases when approaching the temperature of the transition from the ferromagnetic to the antiferromagnetic state.