Physics of the Solid State (PHYS SOLID STATE+)

Publications in this journal

• Article: Ferroelastic phase transitions in (NH4)(2)TaF7

  E I Pogorel'tsev, S V Mel'nikova, A V Kartashev, M S Molokeev, M V Gorev, I N Flerov, N M Laptash
  [show abstract] [hide abstract]
  ABSTRACT: The heat capacity, unit cell parameters, permittivity, optical properties, and thermal expansion of the (NH4)(2)TaF7 compound with a seven-coordinated anion polyhedron have been measured. It has been found that the compound undergoes two successive phase transitions with the symmetry change: tetragonal -> (T (1) = 174 K) orthorhombic -> (T (2) = 156 K) tetragonal. The ferroelastic nature of structural transformations has been established, and their entropy and susceptibility to hydrostatic pressure have been determined.
  Physics of the Solid State 03/2013; 55(3):611-618.
• Article: Investigation into phase diagrams of the fluorine-oxygen system: Ferroelastic-antiferroelectric (NH4)(2)WO2F4-(NH4)(2)MoO2F4

  E V Bogdanov, E I Pogoreltsev, S V Mel'nikova, M V Gorev, I N Flerov, M S Molokeev, A V Kartashev, A G Kocharova, N M Laptash
  [show abstract] [hide abstract]
  ABSTRACT: Thermal, physical, structural, optical, and dielectric investigations have been performed for oxyfluoride solid solutions (NH4)(2)W1 - x Mo (x) O2F4 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.6, 0.8, 1). The character of the influence of the chemical and hydrostatic pressures on the stability of the parent (space group Cmcm) and distorted ferroelastic and antiferroelectric phases has been determined by analyzing the temperature-pressure, unit cell volume-composition, and temperature-composition phase diagrams. The specific features of the nature and mechanism of the phase transitions have been discussed using the available data on the structural, entropy, and dielectric parameters.
  Physics of the Solid State 02/2013; 55(2):409-418.
• Article: Optical Properties of Low-Dimensional Organic Conductors with Differently Oriented Conducting Layers: (EDT-TTF)3Hg2Br6 and (EDT-TTF)3Hg(SCN)3I0.5(PhCl)0.5.

  R.M. Vlasova, B.V. Petrov, V.N. Semkin, E.I. Zhilyaeva, S.A. Torunova
  [show abstract] [hide abstract]
  ABSTRACT: Spectral optical investigations of two low-dimensional organic molecular conductors with differently oriented conducting layers of ethylenedithiotetrathiafulvalene (EDT–TTF) molecules, namely, the (EDT–TTF)3Hg2Br6 and (EDT–TTF)3Hg(SCN)3I0.5(PhCl)0.5 single crystals, have been carried out. The polarized reflectance spectra of the single crystals have been measured in the frequency range 700–6500 cm–1 (0.087–0.810 eV) at temperatures from 300 to 15 K. The optical conductivity spectra have been obtained using the Kramers–Kronig relations, and their quantitative analysis has been performed in terms of a theoretical model that takes into account electron–electron correlations in the approximation of the Hubbard Hamiltonian for trimerized stacks, the vibronic coupling, and the influence of the counterion on the electronic states in the trimer.
  Physics of the Solid State 01/2013; 55(1):131-139.
• Article: Magnetic and electrical properties of bismuth cobaltite Bi-24(CoBi)O-40 with charge ordering

  S S Aplesnin, L V Udod, M N Sitnikov, D A Velikanov, M V Gorev, M S Molokeev, A I Galyas, K I Yanushkevich
  [show abstract] [hide abstract]
  ABSTRACT: The compound Bi-24(CoBi)O-40 has been synthesized using the solid-phase reaction method. The temperature and field dependences of the magnetic moment in the temperature range 4 K < T < 300 K and the temperature dependences of the EPR line width and g-factor at temperatures 80 K < T < 300 K have been investigated. The electrical resistivity and thermoelectric power have been measured in the temperature range 100 K < T < 1000 K. The activation energy has been determined and the crossover of the thermoelectric power from the phonon mechanism to the electron mechanism with variations in the temperature has been observed. The thermal expansion coefficient of the samples has been measured in the temperature range 300 K < T < 1000 K and the qualitative agreement with the temperature behavior of the electrical resistivity has been achieved. The electrical and structural properties of the compound have been explained in the framework of the model of the electronic-structure transition with inclusion of the exchange and Coulomb interactions between electrons and the electron-phonon interaction.
  Physics of the Solid State 10/2012; 54(10):2005-2014.
• Article: Magnetic state of the GdFeTi2O7 compound

  G A Petrakovskii, T V Drokina, D A Velikanov, O A Bayukov, M S Molokeev, A V Kartashev, A L Shadrina, A A Mitsuk
  [show abstract] [hide abstract]
  ABSTRACT: The X-ray diffraction, Mossbauer, calorimetric, and magnetic characteristics of zirconolite GdFeTi2O7 have been measured to determine the ground magnetic state. A kink dependent on the magnetic prehistory of the sample has been revealed in the temperature dependence of the magnetic moment at T = 3 K. Mossbauer spectroscopy has confirmed the nonequivalence of the iron ion positions in GdFeTi2O7. The experimental data obtained allow the conclusion on the formation of a spin glass state with the freezing temperature T (f) = 3 K in the GdFeTi2O7 compound.
  Physics of the Solid State 09/2012; 54(9):1813-1816.
• Article: Caloric characteristics of PbTiO3 in the temperature range of the ferroelectric phase transition

  E A Mikhaleva, I N Flerov, M V Gorev, M S Molokeev, A V Cherepakhin, A V Kartashev, N V Mikhashenok, K A Sablina
  [show abstract] [hide abstract]
  ABSTRACT: The heat capacity and thermal expansion of the PbTiO3 ceramic sample have been measured in the temperature range 80-970 K. The electrocaloric and barocaloric efficiencies of lead titanate in the ferroelectric phase transition range have been investigated by analyzing the experimental data in terms of the thermodynamic theory of phase transitions, the electrical equation of state P(T, E), the Pippard equation, and the S(T, p) diagram.
  Physics of the Solid State 09/2012; 54(9):1832-1840.
• Article: Ferroelectricity and pressure-induced phase transitions in HgTiO3

  A. I. Lebedev
  [show abstract] [hide abstract]
  ABSTRACT: Using ab initio density functional theory, the ground state of mercury titanate is determined and phase transitions occurring in it at pressures P ≤ 210 kbar are analyzed. It is shown that the R3c structure experimentally observed in HgTiO3 is metastable at P = 0. The ground state structure at T = 0 varies according to the scheme R3c→R3-c→Pbnm with increasing pressure in agreement with available experimental data. It is shown that the appearance of ferroelectricity in HgTiO3 at P = 0 is associated with an unstable soft mode. Some properties of crystals in the R-3c phase are calculated, in particular, the band gap in the GW approximation (E g = 2.43 eV), which is in better agreement with experimental data than the value obtained in the LDA approximation (1.49 eV). An analysis of the thermodynamic stability explains why the synthesis of mercury titanate is possible only at high pressures.
  Physics of the Solid State 08/2012; 54(8):1663-1668.
• Article: Electronic structure of bismuth ferrite and hematite single crystals: X-ray photoelectron study and calculation

  A. T. Kozakov, K. A. Guglev, V. V. Ilyasov, I. V. Ershov, A. V. Nikol’skii, V. G. Smotrakov, V. V. Eremkin
  [show abstract] [hide abstract]
  ABSTRACT: The X-ray photoelectron spectra of the inner levels and valence bands of the surfaces of BiFeO3 and Fe2O3 single crystals have been measured using X-ray photoelectron spectroscopy on an ESCALAB 250 X-ray photoelectron microprobe with monochromatization of X-ray radiation of the AlK α line. The ab initio calculations have been performed by the full-potential pseudopotential method in terms of the density functional theory (Quantum-Espresso program package). The band structure and the total and partial densities of states have been calculated for the BiFeO3 and Fe2O3 systems. A comparison of the theoretical and experimental results has demonstrated good agreement between theory and experiment.
  Physics of the Solid State 05/2012; 53(1):41-47.
• Article: Lifetime of resonance states of the continuous electronic spectrum of a quantum-well Cu(001) film

  G. V. Wolf, Yu. P. Chuburin
  [show abstract] [hide abstract]
  ABSTRACT: The dispersion relation and lifetimes of the resonances in elastic scattering of electrons with energies above the edge of the continuous spectrum of a (001) fcc copper film have been calculated for the first time. It has been found that there is a resonance band with very long lifetimes in a specific region of electron quasi-momenta in the direction Ȳ of the two-dimensional Brillouin zone. The specificity of these states should be taken into account when describing the transport of sliding low-energy electron beams in a quantum-well copper film.
  Physics of the Solid State 05/2012; 53(7):1499-1503.
• Article: Piezoelectricity in protein amino acids

  V. V. Lemanov, S. N. Popov, G. A. Pankova
  [show abstract] [hide abstract]
  ABSTRACT: The piezoelectric activity of protein amino acids and their compounds has been measured using the pulse method at a frequency of 10 MHz. It has been established that, at room temperature, the piezoelectric effect is not observed in α-glycine (achiral amino acid) and protein amino acids of the L modification, namely, methionine, phenylalanine, and tryptophan. An assumption has been made that this phenomenon is associated with the enhanced damping of elastic vibrations excited in samples due to the piezoelectric effect.
  Physics of the Solid State 05/2012; 53(6):1191-1193.
• Article: Anisotropic magnetoresistance of partially relaxed SrRuO3 films

  Yu. A. Boikov, V. A. Danilov
  [show abstract] [hide abstract]
  ABSTRACT: The SrRuO3 films (50 nm thick) grown by laser evaporation on (001)(LaAlO3)0.3 + (Sr2AlTaO6)0.7 substrates were under partially relaxed biaxial compressive mechanical stresses. The films consisted of crystallites with The SrRuO3 films (50 nm thick) grown by laser evaporation on (001)(LaAlO3)0.3 + (Sr2AlTaO6)0.7 substrates were under partially relaxed biaxial compressive mechanical stresses. The films consisted of crystallites with lateral dimensions of 40–100 nm and a relative azimuthal misorientation of about 0.9°. Ferromagnetic ordering of spins in lateral dimensions of 40–100 nm and a relative azimuthal misorientation of about 0.9°. Ferromagnetic ordering of spins in the SrRuO3 films was manifested by a change in the slope of the temperature dependence of their electrical resistivity ρ at T ≈ 155 K. For a magnetic field H parallel to the measuring current, the maximum values (∼7.5%) of the magnetoresistance MR = [ρ(μ0 the SrRuO3 films was manifested by a change in the slope of the temperature dependence of their electrical resistivity ρ at T ≈ 155 K. For a magnetic field H parallel to the measuring current, the maximum values (∼7.5%) of the magnetoresistance MR = [ρ(μ0 H = 5 T) − ρ(μ0 H = 5 T) − ρ(μ0 H = 0)]/ρ(μ0 H = 0)]/ρ(μ0 H = 0) were observed at temperatures of about 100 K. At T = 95 K (μ0 H = 0) were observed at temperatures of about 100 K. At T = 95 K (μ0 H = 5 T), the anisotropic magnetoresistance of the films was 8% and increased by a factor of approximately 1.5 with decreasing H = 5 T), the anisotropic magnetoresistance of the films was 8% and increased by a factor of approximately 1.5 with decreasing temperature to 4.2 K. temperature to 4.2 K.
  Physics of the Solid State 05/2012; 53(6):1298-1301.
• Article: Magnetic phase diagram of the spin-valve structure with an antiferromagnetic oxide layer

  A. I. Morosov, I. A. Morosov
  [show abstract] [hide abstract]
  ABSTRACT: The magnetic phase diagram of a three-layer ferromagnet-antiferromagnet-ferromagnet structure with an antiferromagnetic oxide layer of variable thickness has been investigated. It has been predicted that there are three ranges of thicknesses in which domain walls created by the frustration of the exchange interaction between the layers have different structures. The structure of these domain walls induced by edges of atomic steps at the interfaces between the layers has been described. The predictions of the theory have been compared with the available experimental results, in particular, with the data indicating the existence of the nanodomain state.
  Physics of the Solid State 05/2012; 53(1):59-66.