Ferromagnetic resonance study of the effect of elastic stresses on the anisotropy of magnetic films

The distribution of the magnitude and direction of the uniaxial magnetic anisotropy field over the area of permalloy films obtained by thermal evaporation in vacuum was studied using a scanning ferromagnetic resonance spectrometer. The films were deposited on glass substrates subjected to bending stress in the presence of an in-plane static magnetic field. Depending on the character of the elastic-stress distribution over a local spot of a film, the uniaxial anisotropy induced by a magnetic field is either enhanced or completely compensated, which is accompanied by a significant change in the direction of the easy axis of magnetization. The observed effects are in good agreement with phenomenological calculations.     

Synthesis and magnetic properties of solid solutions In<Subscript>1–<Emphasis Type="Italic">x</Emphasis></Subscript>Ga<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Sb〈Mn〉

Manganese-doped solid solutions In_1–x Ga _x Sb (x = 0.05, 0.1, 0.5, 0.9, 0.95) were synthesized. It was found that, in samples of the compositions In_0.95Ga_0.05Sb〈Mn〉 and In_0.05Ga_0.95Sb〈Mn〉, a homogeneous substitutional solid solution forms, into which manganese-containing clusters are incorporated. The clusters are mainly located at crystal lattice defects—grain boundaries and dislocations. The ferromagnetic properties of the obtained samples at room temperature and higher are caused by clusters Mn_1+x Sb, the effective size of which is about 180–300 nm.     

High-temperature heat capacity of erbium titanate with a pyrochlore structure

Erbium titanate with a pyrochlore structure has been synthesized by a ceramic method from stoichiometric Er₂O₃–TiO₂ mixtures at 1673–1773 K. The high-temperature heat capacity of Er₂Ti₂O₇ (320–1000 K) has been studied by differential scanning calorimetry. The thermodynamic functions of this oxide compound—enthalpy and entropy changes and reduced Gibbs—have been calculated from the experimental dependence C _P = f(T).     

High-temperature heat capacity of stannates Er<Subscript>2</Subscript>Sn<Subscript>2</Subscript>O<Subscript>7</Subscript> and Tm<Subscript>2</Subscript>Sn<Subscript>2</Subscript>O<Subscript>7</Subscript>

Erbium stannate Er₂Sn₂O₇ and thulium stannate Tm₂Sn₂O₇ with a pyrochlore-type structure were produced by solid-phase synthesis by calcining stoichiometric mixtures of the respective oxides in air at 1473 K for 240 and 200 h. The high-temperature heat capacity of Er2Sn2O7 and Tm₂Sn₂O₇ was studied by differential thermal calorimetry at 353–1000 K. From the experimental dependences C _P = f(T), the thermodynamic functions (enthalpy change, entropy change, and reduced Gibbs free energy) of oxide compounds were calculated.     

Polarization in the quasielastic scattering of 1-GeV/c protons on light nuclei

Polarization measurements in the A(p, 2p)B reactions on ⁶Li, ⁷Li, and ²⁸Si nuclei at a proton-beam energy of 1 GeV were performed in a kinematically complete experiment. By using a two-arm magnetic spectrometer, two secondary protons were recorded in coincidence at asymmetric scattering angles of θ₁=15°?26° and θ₂=58.6° for residual-nucleus momenta in the range K _B=0–150 MeV/c. Either arm of the spectrometer was equipped with polarimeters based on proportional chambers. The data coming from this experiment are analyzed within the distorted-wave impulse approximation. It is shown that the polarization of recoil protons formed at angle θ₂ in the interaction featuring a proton from the P shell of the ⁷Li nucleus can be described under the assumption of an effective intranuclear-proton polarization by using the single-particle shell-model wave function of the nucleus. Our data on the polarizations of the two protons from the reaction (p, 2p) on a ²⁸Si nucleus also suggest the effective polarization of the protons in the D shell of the ²⁸Si nucleus. It is found that, for high recoil-nucleus momenta of K _B≥90 MeV/c, the effective polarization of the protons in the P shell of the ⁶Li nucleus—this polarization was discovered in studying the polarization of recoil protons in the reaction ⁶Li(p, 2p)⁵He—cannot be described within the shell model assuming LS coupling. As might have been expected, the polarization of recoil protons knocked out from the S shells of the ⁶Li and ⁷Li nuclei comply well with the predictions obtained in the impulse approximation with allowance for the depolarization effect alone.     

Micromagnetic calculation of the equilibrium distribution of magnetic moments in thin films

A new approach has been proposed for determining an equilibrium configuration of magnetic moments in condensed matter in terms of its discrete model. The solution to this problem is reduced to a system of linear inhomogeneous equations with undetermined Lagrange multipliers. The possibility of numerically solving these systems has been shown using a modified power method. The efficiency of the method has been demonstrated for the model of a thin magnetic film with a nonuniform distribution of the uniaxial magnetic anisotropy over the area. The dependence of the coercive force on the uniaxial anisotropy of nanocrystallites, their exchange interaction, and other parameters of samples has been investigated.     

Fullerit C<Subscript>60</Subscript> single crystals grown on earth and in space

Fullerit C₆₀ single crystals were grown by sublimation on Earth and under microgravity during the FOTON-M3 mission using the same growth parameters and the same multizoned electrovacuum POLIZON-M furnace. IR spectroscopy and X-ray measurements revealed the considerably better crystal structure of the crystals grown under microgravity.     

Effect of Ethanedioic Acid Additives on the Dissolution of Manganese Oxides in Sulfuric Acid Solution

The effect of ethanedioic acid additives on the rate of manganese(IV) oxide dissolution in sulfuric acid solutions was studied by kinetic and electrochemical methods. Interaction modes were established, and some details of the studied process mechanism were elucidated. Interaction schemes corresponding to the observed kinetic dependences were proposed.     

Interaction between lanthanide cuprates and hydrochloric acid

The interaction between lanthanide cuprates Ln₂CuO_{4 − δ} (Ln = La-Gd) and hydrochloric acid is investigated. The effects of solution pH, temperature, and the nature of the rare-earth element ion on dissolution is studied. The formal order of the reaction in the acid is the same for all the substances under study and is 0.53 ± 0.05. The effective activation energy for the process is 40 ± 0.5 kJ/mol. A scheme of Ln₂CuO_{4 − δ} interaction with HCl is proposed.