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The frequency dependences of the real (ε') and imaginary (ε'') parts of the complex dielectric permittivity, the dielectric loss tangent (tanδ), and the ac conductivity (σac) in the frequency range f = 5 × 104–3.5 × 107 Hz have been studied in the TlIn1 –xErxS2 (0 ≤ x ≤ 0.01) crystals synthesized in this work. It is found that, in TlIn1 –xErxS2, the relaxation dispersions of ε' and ε'' take place. The effect of the erbium concentration (Er) in the TlIn1 –xErxS2 crystals on their dielectric coefficients has been studied. At high frequencies, the ac conductivity of the TlIn1 –xErxS2 crystals obeys the relationship σac ~ f 0.8, which is characteristic of the hopping mechanism of the charge transfer over states localized near the Fermi level. The parameters of the states localized in the forbidden band of TlIn1 –xErxS2 and the influence of the chemical composition of the crystals on these parameters are estimated. [ABSTRACT FROM AUTHOR]

Abstract Altshuler and Aronov (AA) have shown that the electron-electron interaction in a weakly-disordered metal suppresses the single-particle density of states (DOS) in the vicinity of the Fermi level (E F). According to the AA theory the suppressed DOS exhibits the energy dependence ∝ | E − E F | valid for | E − E F | smaller than a certain correlation energy U co. Recent experiments have shown that at energies larger than U co the DOS exhibits a states-conserving dependence on energy, namely, the states removed from near the Fermi level are found at energies above U co in the energy range of about 3 U co. In this work the AA effect is studied beyond the low energy limit theoretically. We consider the AA model in which the electrons interact via the statically screened Coulomb interaction and the modification of the DOS is due to the exchange part of the electron self-energy. We derive the states-conserving DOS heuristically. Namely, we show that the self-energy consists of a diverging part (which we skip on physical grounds) and of the small part of the order of the pair Coulomb energy. This small part gives the states-conserving DOS which is in qualitative accord with experimental observations at energies above U co and which reproduces the AA result at energies below U co. Highlights • We study theoretically the Altshuler-Aronov effect beyond the low energy limit. • We derive the electron density of states valid at any energy. • At low energies our result reproduces the result of Altshuler and Aronov. • At high energies it conserves the states in qualitative accord with experiment. [ABSTRACT FROM AUTHOR]

• Structural, electronic, magnetic properties of orthorhombic PrCuO 3 perovskites scrutinised by DFT. • Computed structural parameters are in good accord with corresponding experimental data. • Energetically-favoured anti-ferromagnetic ordering of bulk PrCuO 3 is promoted. • Semi-conducting nature of bulk orthorhombic PrCuO 3 perovskites established. • Computed band gap of most stable AF state is 1.39 eV, indicating potential high degree of suitability for solar-energy applications. We performed Density-Functional Theory calculations on the recently-synthesised perovskite PrCuO 3 structure. PBE + U and hybrid-DFT (HSE06) calculations reveal that the PrCuO 3 -structure energy bands cannot cross the Fermi level in the Total Density of States – indicating semi-conducting behaviour. The bond geometries and bond angles agree well with their experimental counterparts. We have explored magnetic-momentum states in the pattern of the Pr and Cu magnetic moments along the [1 1 1] direction – elucidating that screening of different magnetic ordering shows that antiferromagnetic (AFM) order is more energetically favoured. Optical-absorption spectra computed HSE06 indicate PrCuO 3 ′s potential solar-energy and technological interest. [ABSTRACT FROM AUTHOR]