Effect of the stresses caused by substrate on the electrical conductivity of ferromagnetic manganite lanthanum–barium films

This is a complex study of the electrophysical and magnetic characteristics of epitaxial manganite La_0.7Ba_0.3MnO₃ (LBMO) films under conditions of crystal structure stresses caused by misfit in the lattice parameters of the LBMO crystal and a substrate. The substrate used had the lattice parameter smaller than that in the LBMO crystal. It is shown that the temperature dependence of the electrical resistance of the films at low temperatures is not dependent on the existence of stresses in the film and agrees well with the calculation with allowance made for the interaction of carriers with magnetic excitations in the presence of strongly correlated electronic states. The study of the ferromagnetic resonance line indicates an inhomogeneity of the ferromagnetic phase in the LBMO films and the increase in the ferromagnetic resonance line width with decreasing temperature.     

Magnetic anisotropy of strained epitaxial manganite films

The in-plane magnetic anisotropy of epitaxial La_0.7Sr_0.3MnO₃ (LSMO) films is studied at room temperature by the following three independent techniques: magnetooptical Kerr effect, ferromagnetic resonance at a frequency of 9.61 GHz, and recording of absorption spectra of electromagnetic radiation at a frequency of 290.6 MHz. The films are deposited onto NdGaO₃ (NGO) substrates in which the (110)NGO plane is tilted at an angle of 0–25.7° to the substrate plane. The uniaxial magnetic anisotropy induced by the strain of the film is found to increase with the tilt angle of the (110)NGO plane. A model is proposed to describe the change in the magnetic anisotropy energy with the tilt angle. A sharp increase in the radio-frequency absorption in a narrow angular range of a dc magnetic field near a hard magnetization axis is detected The anisotropy parameters of the LSMO films grown on (110)NGO, (001)SrTiO₃, and (001)[(LaAlO₃)_0.3 + (Sr₂AlTaO₆)_0.7] substrates are compared.     

Chemisorption,Morphology, and Structure of a n‐Type Perylene Diimide Derivative at the Interface with Gold: Influence on Devices from Thin Films to Single Molecules

We have investigated thin films of a perylene diimide derivative with a cyano‐functionalized core (PDI‐8CN₂) deposited on Au(111) single crystals from the monolayer to the multilayer regime. We found that PDI‐8CN₂ is chemisorbed on gold. The molecules experience a thickness‐dependent reorientation, and a 2D growth mode with molecular stepped terraces is achieved adopting low deposition rates. The obtained results are discussed in terms of their impact on field effect devices, also clarifying why the use of substrate/contact treatments, decoupling PDI‐8CN₂ molecules from the substrate/contacts, is beneficial for such devices. Our results also suggest that perylene diimide derivatives with CN bay‐functionalization are very promising candidates for single‐molecule electronic devices.     

On the use of the finite difference method in a calculation of vibration-rotation energies

The use of the finite difference method to obtain a Taylor series expansion of a potential energy function for a subsequent calculation of the rovibration energies of molecules is considered. A method is proposed that allows the stability of a finite-difference scheme to be increased against the computational inaccuracy upon numerical expansion of a multidimensional potential energy function into a high-order Taylor series. The method is based on the successive elimination of calculated expansion coefficients of a higher order in calculating the lower-order coefficients by the finite difference method. The approach is illustrated for the example of the CO and H₂S molecules.     

Phase transitions investigation in ZnTe by thermoelectric power measurements at high pressure

The pressure-induced phase transitions were studied in ZnTe by the thermoelectric power (S) technique. For the high-pressure trigonal phase P3₁21 cinnabar the large thermopower values S≈+400 correspond to semiconductor hole conductivity. During a transition into the orthorhombic structure Cmcm the value of S dropped by 40-50 times indicating metallic hole conductivity, like in the high pressure phases of other chalcogenides of II Group (HgSe, HgTe, CdTe) with Cmcm structure. In a transient region between the trigonal and orthorhombic phase (especially under decreasing pressure) a novel phase has been observed with a negative value of S. By analogy with other Zn and Cd chalcogenides whose NaCl phases have an electron type of conductivity the phase observed may have a NaCl structure.     

Natural Electromagnetic Waves in a Circular Waveguide with Chiral Layers

The solution of the dispersion equation is analyzed for some natural modes of a two-layer circular waveguide with chiral mirror layers.     

Thermoelectric power, magnetoresistance of lead chalcogenides in the region of phase transitions under pressure

The longitudinal and transverse thermomagnetic Nernst-Ettingshausen (N-E) effects were measured at ultrahigh pressure up to 20 GPa under closure of semiconductor gap at NaCl- and GeS-type phases of n-PbTe, p-PbSe and p-PbS. Near ∼3 GPa, the maxima of N-E effects and magnetoresistance (and hence of mobility of charge carriers) attributed to gapless state for PbTe and PbSe were established. The reversible sign inversion of transverse N-E effect indicating the change in scattering mechanism of charge carries have been revealed at high pressure phase of PbSe. The lowering of thermomagnetic effects with pressure gave the evidence of indirect semiconductor gap at high pressure GeS-type phases in contrary to NaCl-phases.     

Shape Memory Effect and Superelasticity in Ti–Ni and Fe–Ni–Co–Ti Single Crystals

The dependence of shape memory effect and superelasticity on the crystal orientation, size, and particle volume fraction is studied for Ti–Ni and Fe–Ni–Co–Ti single crystals. The shape memory effect and superelasticity are shown to decrease with increase in the particle volume fraction and depend on the number of crystallographic variants of particles that can vary due to aging under loading. The influence of disperse particles undergoing no martensite transformations on the martensitic crystal growth and their fine structure is examined.     

Josephson effect in hybrid oxide heterostructures with an antiferromagnetic layer

Josephson coupling between an s- and d-wave superconductor through a 50 nm thick Ca1-xSrxCuO2 antiferromagnetic layer was observed for the hybrid Nb/Au/Ca1-xSrxCuO2/YBa2Cu3O7-delta heterostructures and investigated as a function of temperature, magnetic field, and applied millimeter-wave electromagnetic radiation. The magnetic field dependence of the supercurrent I(c)(H) exhibits anomalously rapid oscillations, which is the first experimental evidence of the theoretically predicted giant magneto-oscillations in Josephson junctions with antiferromagnetic interlayers.