Showing papers by "A. S. Prokhorov published in 2011"
TL;DR: In this paper, the authors analyzed the optical conductivity and permittivity spectra of Ba(Fe{}_{0.9}$Co${}_{ 0.1}$) and As{}{2}$ films with a generalized two-band BCS model with intraband and interband pairing interactions.
Abstract: The optical conductivity and permittivity spectra of Ba(Fe${}_{0.9}$Co${}_{0.1}$)${}_{2}$As${}_{2}$ films (${T}_{c}=20 \text{K}$) are analyzed together with the literature data on photoemission and specific heat. In the superconducting state at all temperatures up to ${T}_{c}$ the temperature dependence of the magnetic field penetration depth is well described within the generalized two-band BCS model with intraband and interband pairing interactions considered. It is shown that the small superconducting energy gap $2{\ensuremath{\Delta}}^{(1)}=3.7\text{meV}$ develops in the electron subsystem while the larger gap $2{\ensuremath{\Delta}}^{(2)}=7.9\text{meV}$ opens in the hole subsystem. The normal state parameters, such as plasma frequency and scattering rate, of electron and hole conduction bands are determined.
33 citations
TL;DR: The spectra of complex permittivity of a Ba2Mg2Fe12O22 single crystal belonging to the family of Y-type hexaferrites have been measured over a wide temperature range (10-300 K) with the aim of determining the dynamic parameters of the phonon and magnetic subsystems in the terahertz and infrared frequency ranges (3-4500 cm−1) as discussed by the authors.
Abstract: The spectra of complex permittivity of a Ba2Mg2Fe12O22 single crystal belonging to the family of Y-type hexaferrites have been measured over a wide temperature range (10–300 K) with the aim of determining the dynamic parameters of the phonon and magnetic subsystems in the terahertz and infrared frequency ranges (3–4500 cm−1). A factor-group analysis of the vibrational modes has been performed, and the results obtained have been compared with the experimentally observed resonances. The oscillator parameters of all nineteen phonon modes of E
u
symmetry, which are allowed by the symmetry of the Ba2Mg2Fe12O22 crystal lattice, have been calculated. It has been found that, at temperatures below 195 and 50 K, the spectral response exhibits new absorption lines due to magnetic excitations.
5 citations
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TL;DR: In this paper, the spectral properties of single crystalline Y-type hexaferrite Ba-,Mg-,Fe-,12)O-,22, and Fe-,12)-O-, 22, were measured at Terahertz and infrared frequencies, 3 - 4500 c--1, and at temperatures 10 to 300 K, for polarization E prp c.
Abstract: Spectra of transmission and reflection coefficients of single crystalline Y-type hexaferrite Ba_(2)Mg_(2)Fe_(12)O_(22) are measured at Terahertz and infrared frequencies, 3 - 4500 c--1, and at temperatures 10 to 300 K, for polarization E prp c. Oscillator parameters of nineteen phonon lines allowed by the R3m crystal lattice symmetry are determined. Absorption lines assignment to vibrational modes of the lattice structural fragments is performed. Below the temperatures of 195 K and 50 K, corresponding to the zero field phase transitions to the proper screw and to the longitudinal-conical spin states, respectively, new absorption lines are discovered whose origin is assigned to the electric-dipole active magnetic excitations.
TL;DR: In the last few decades, significant progress has been achieved in the development of generators and detectors of terahertz radiation (at frequencies in the range from ≈300 GHz to ≈3 THz) as mentioned in this paper.
Abstract: In the last few decades, significant progress has been achieved in the development of generators and detectors of terahertz radiation (at frequencies in the range from ≈300 GHz to ≈3 THz). Different terahertz spectroscopic techniques have been widely used now in investigating semiconductors, superconductors, molecular magnets, multiferroics, metamaterials, and other promising objects. It has been demonstrated that terahertz spectroscopy offers wide but not completely realized possibilities for studying quantum phase transitions in electron-correlated systems.