Homogeneity region of erbium manganite Er<Subscript>2 − <Emphasis Type=Italic>x</Emphasis></Subscript>Mn<Subscript><Emphasis Type=Italic>x</Emphasis></Subscript>O<Subscript>3 ± δ</Subscript> in air

The solubility ranges of Er₂O₃ and Mn₃O₄ oxides and ErMn₂O₅ manganite in ErMnO_{3 ± δ} are determined for the temperature range 900–1400°C.     

Cascade of phase transitions in the Fe<Subscript>1 − <Emphasis Type=Italic>x</Emphasis></Subscript>Co<Subscript><Emphasis Type=Italic>x</Emphasis></Subscript> monolayer

The reorientation phase transitions occurring in FeCo alloy monolayers have been investigated as a function of the cobalt concentration with inclusion of the magnetodipole and magnetoelastic interactions. The kinetic values of the cobalt concentration corresponding to the phase transition points have been determined and the phase diagram of the system under investigation has been constructed.     

Absorption spectra of thin layers of solid solutions Cs<Subscript>2</Subscript>(Cd<Subscript>1 − <Emphasis Type=Italic>x</Emphasis></Subscript>Zn<Subscript><Emphasis Type=Italic>x</Emphasis></Subscript>)I<Subscript>4</Subscript>

The excitonic absorption spectra of thin films of ferroelectric Cs₂CdI₄ and Cs₂ZnI₄ solid solutions are studied for the first time. It is found that, within the whole range of molar concentrations x, the spectra of Cs₂(Cd_{1 − x} Zn _x )I₄ comprise two bands that originate from the bands of the two compounds. It is shown that the exciton transfer occurs most efficiently between the tetrahedrons CdI₄ and ZnI₄ along the b axis of the crystal. Unusual behavior of the concentration with regards to the maxima of long-wavelength excitonic bands E _m (x) agrees well with the developed theory that takes into account dependence on x of the matrix element of the intertetrahedron exciton transfer and that is similar to the theory of Davydov’s splitting in molecular crystals.     

Laser assisted electrochemical preparation of micro and nanopores in Ga<Subscript><Emphasis Type=Italic>x</Emphasis></Subscript>In<Subscript>1−<Emphasis Type=Italic>x</Emphasis></Subscript>P

We report on the preparation of Ga(x)In(1−x)P/GaAs lattice matched heterostructures by liquid phase epitaxy and their electrochemical etching to prepare porous networks. We show that the process of formation of pores strongly depends on the electrolyte, on the applied current/voltage anodization regime, and that illumination is a crucial factor in obtaining fine porous structures with a high degree of self-organization.     

Magnetic properties of multiferroics Bi<Subscript>1 – <Emphasis Type=Italic>x</Emphasis></Subscript>Sm<Subscript><Emphasis Type=Italic>x</Emphasis></Subscript>FeO<Subscript>3</Subscript> synthesized under high pressure

The magnetic properties of the multiferroics obtained upon isovalent substitution of samarium cations for bismuth cations in BiFeO₃. The samples have been synthesized by solid-phase reactions under conditions of a cold pressing at high (4 GPa) pressure. The correlation between the structure and the magnetic properties of the multiferroics has been found based on analyzing the experimental data.     

Spin glass effects in Co<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Mn<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>S solid solutions

The magnetization, resistance, permittivity, and thermal expansion coefficient of cation-substituted sulfides Co _x Mn_{1 ? x} S have been measured. The relationship between the magnetic, electric, and elastic subsystems of Co _x Mn_{1 ? x} S solid solutions is established and the features of physical properties characteristic of multiferroics, induced by orbital-charge ordering, are found.     

Temperature Dependence of the Transmission Spectra of Silicate Glasses Containing CdS<Subscript>1−<Emphasis Type=Italic>x</Emphasis></Subscript>Se<Subscript><Emphasis Type=Italic>x</Emphasis></Subscript> Semiconducting Nanocrystals

The transmission spectra of silicate glasses containing CdS_{1 − x} Se _x semiconducting nanocrystals of various sizes are investigated in the temperature range 20–300°C. It is shown that for explaining optical properties of these materials, not only the nanocrystal sizes, but also the structural changes occurring in nanocrystals during their formation must be taken into account.     

Magnetic behaviour of doped dimer compounds Sr<Subscript>3</Subscript>Cr<Subscript>2−<Emphasis Type=Italic>x</Emphasis></Subscript>M<Subscript><Emphasis Type=Italic>x</Emphasis></Subscript>O<Subscript>8</Subscript> (M = V,Mn)

Wilson chains, based on a logarithmic discretization of a continuous spectrum, are widely used to model an electronic (or bosonic) bath for Kondo spins and other quantum impurities within the numerical renormalization group method and other numerical approaches. In this short note we point out that Wilson chains can not serve as thermal reservoirs as their temperature changes by a number of order ΔE when a finite amount of energy ΔE is added. This proves that for a large class of non-equilibrium problems they cannot be used to predict the long-time behavior.     

Magnetic properties of single crystals of the Cr<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Mn<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>S solid solutions (0 ≤ <Emphasis Type="Italic">x</Emphasis> < 0.3)

The Cr _x Mn_{1 − x} S single crystals have been synthesized based on manganese monosulfide as a result of cation substitution, and their magnetic properties have been studied. It has been established that the Cr _x Mn_{1 − x} S solid solutions with a face-centered cubic NaCl structure are formed in the concentration region 0 ≤ x < 0.3. The unit cell parameter of the solid solution decreases as the degree of substitution increases due to the variation in the ionic radius of cations. These substances are antiferromagnets. An increase in the degree of cation substitution in the Cr _x Mn_{1 − x} S solid solutions is accompanied by a decrease in the number of 3d electrons in the d shell of manganese monosulfide and causes a decrease in the magnetic transition temperature from 149 K (x = 0) to 96 K (x = 0.29), which differs from previously known results.     

Statistical mechanics of cation ordering and lattice dynamics of PbZr<Subscript>x</Subscript>Ti<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>3</Subscript> solid solutions

An effective Hamiltonian for Zr-Ti cation ordering in PbZr_xTi_1?xO₃ solid solutions is written out. To determine the parameters of the effective Hamiltonian, a nonempirical calculation is performed within an ionic-crystal model taking into account the deformation and dipole and quadrupole polarizabilities of ions. The thermodynamic properties of cation ordering are studied using the Monte Carlo method. The calculated phase transition temperatures (180 and 250 K for the concentrations x=1/3 and 1/2, respectively) are much lower than the melting temperature of the compound under study. At such temperatures, the ordering kinetics is frozen and, in reality, the phase transition to the ordered phase does not occur, in agreement with experimental observations. Within the same ionic-crystal model, we calculated the high-frequency permittivity, Born dynamic charges, and the lattice vibration spectrum for a completely disordered phase and certain ordered phases. It is shown that soft vibration modes, including ferroelectric ones, exist in the lattice vibration spectrum of both the completely disordered and the ordered phases.