Author
A. S. Prokhorov
Other affiliations: Moscow Institute of Physics and Technology
Bio: A. S. Prokhorov is an academic researcher from Russian Academy of Sciences. The author has contributed to research in topics: Terahertz radiation & Dielectric. The author has an hindex of 17, co-authored 80 publications receiving 899 citations. Previous affiliations of A. S. Prokhorov include Moscow Institute of Physics and Technology.
Papers published on a yearly basis
Papers
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TL;DR: In this article, the backward-wave oscillators (BWOs) were used for terahertz-sub-Terahertz (THz-subTHz) spectrometers, based on continuously frequency-tunable coherent sources of radiation.
Abstract: Modern Terahertz-subTerahertz (THz-subTHz) spectrometers, based on continuously frequency-tunable coherent sources of radiation, the backward-wave oscillators (BWOs), are described which cover the frequencies v = 1 cm−1 − 50 cm−1 (0.03 − 1.5 THz) and allow for measurements at temperatures 2 − 1000 K, also in magnetic fields. They allow for direct determination of spectra of any optical parameter of a material at millimeter-submillimeter wavelengths, the domain where infrared or microwave spectrometers encounter serious methodological difficulties. We report on new technical abilities of the quasioptical BWO-spectrometers and discuss their main components. We demonstrate abilities of the THz-subTHz BWO-spectroscopy by presenting some latest results on measurements of dielectric, conducting, superconducting and magnetic materials.
131 citations
TL;DR: The present study places separate H2O molecules in the structural channels of a beryl single crystal so that they are located far enough to prevent hydrogen bonding, but close enough to keep the dipole–dipole interaction, resulting in incipient ferroelectricity in the water molecular subsystem.
Abstract: Water is characterized by large molecular electric dipole moments and strong interactions between molecules; however, hydrogen bonds screen the dipole-dipole coupling and suppress the ferroelectric order. The situation changes drastically when water is confined: in this case ordering of the molecular dipoles has been predicted, but never unambiguously detected experimentally. In the present study we place separate H2O molecules in the structural channels of a beryl single crystal so that they are located far enough to prevent hydrogen bonding, but close enough to keep the dipole-dipole interaction, resulting in incipient ferroelectricity in the water molecular subsystem. We observe a ferroelectric soft mode that causes Curie-Weiss behaviour of the static permittivity, which saturates below 10 K due to quantum fluctuations. The ferroelectricity of water molecules may play a key role in the functioning of biological systems and find applications in fuel and memory cells, light emitters and other nanoscale electronic devices.
67 citations
TL;DR: In this article, the polar phonon modes in BaFe12O19 single crystal were studied in the temperature range from 6 to 300 K by polarized infrared spectroscopy, and it was shown that the phonon spectrum of the crystal is strongly anharmonic and unstable with respect to long-wavelength fluctuations of the dielectric permittivity along the hexagonal axis.
Abstract: The polar phonon modes in BaFe12O19 single crystal are studied in the temperature range
from 6 to 300 K by polarized infrared spectroscopy. The phonon spectrum of the crystal is
strongly anharmonic and unstable with respect to long-wavelength fluctuations of
the dielectric permittivity along the hexagonal axis. Our results suggests that in
BaFe12O19 hexaferrite symmetry lowering to the polar phase with
the space group P63
mc can be
expected.
55 citations
TL;DR: In this article, the T-x phase diagram has been revised and the compensation points of spontaneous weak ferromagnetic moment have been observed for pure SmMnO 3 and for low doped compositions (0 ≤ x ≤ 0.05).
Abstract: Magnetic and electrical properties of Sm 1-x Sr x MnO 3 (0 ≤ x ≤ 0.8) single crystals have been studied and the T-x phase diagram has been revised. The compensation points of spontaneous weak ferromagnetic moment have been observed for pure SmMnO 3 and for low doped compositions (0 ≤ x ≤ 0.05). For 0.4 ≤ x ≤ 0.475 the ferromagnetic ordering occurs as a first-order phase transition. It is shown that in a magnetic field the temperature of this transition increases and the transition becomes broader, which results in the appearance of a critical point (T cr ≃ 193 K, H cr ≃ 68 kOe for x = 0.45). Another transition, accompanied by a reduction of magnetization and noticeable anisotropy of magnetization curves, has been observed at low temperature T s ≃ 40 K. Below the Neel temperature, a pure antiferromagnetic state without spontaneous magnetization has been observed for 0.5 ≤ x ≤ 0.575, while for 0.6 ≤ x ≤ 0.675 an additional low-temperature transition to a new phase with a non-zero weak-ferromagnetic moment has been found.
49 citations
TL;DR: In this article, single-domain Sr1−x/12Cax/12Fe12−xAlxO19 particles are synthesized by a simple citrate auto-combustion method.
46 citations
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TL;DR: This review attempts to provide an overview of the research relevant to the structural and physical properties, fabrication methods, and electronic devices of few-layer MoS2.
Abstract: Due to the recent expanding interest in two-dimensional layered materials, molybdenum disulfide (MoS2) has been receiving much research attention. Having an ultrathin layered structure and an appreciable direct band gap of 1.9 eV in the monolayer regime, few-layer MoS2 has good potential applications in nanoelectronics, optoelectronics, and flexible devices. In addition, the capability of controlling spin and valley degrees of freedom makes it a promising material for spintronic and valleytronic devices. In this review, we attempt to provide an overview of the research relevant to the structural and physical properties, fabrication methods, and electronic devices of few-layer MoS2. Recent developments and advances in studying the material are highlighted.
1,125 citations
TL;DR: In this paper, the capabilities for vacuum electronic device (VED) sources of powerful terahertz (THz) and near-THz coherent radiation, both CW or average and pulsed, were evaluated.
Abstract: Recent research and development has been incredibly successful at advancing the capabilities for vacuum electronic device (VED) sources of powerful terahertz (THz) and near-THz coherent radiation, both CW or average and pulsed. Currently, the VED source portfolio covers over 12 orders of magnitude in power (mW-to-GW) and two orders of magnitude in frequency (from ; 10 THz). Further advances are still possible and anticipated. They will be enabled by improved understanding of fundamental beam-wave interactions, electromagnetic mode competition and mode control, along with research and development of new materials, fabrication methods, cathodes, electron beam alignment and focusing, magnet technologies, THz metrology and advanced, broadband output radiation coupling techniques.
860 citations
TL;DR: In this article, the authors review studies of the electromagnetic response of various classes of correlated electron materials including transition metal oxides, organic and molecular conductors, intermetallic compounds with $d$- and $f$-electrons as well as magnetic semiconductors.
Abstract: We review studies of the electromagnetic response of various classes of correlated electron materials including transition metal oxides, organic and molecular conductors, intermetallic compounds with $d$- and $f$-electrons as well as magnetic semiconductors. Optical inquiry into correlations in all these diverse systems is enabled by experimental access to the fundamental characteristics of an ensemble of electrons including their self-energy and kinetic energy. Steady-state spectroscopy carried out over a broad range of frequencies from microwaves to UV light and fast optics time-resolved techniques provide complimentary prospectives on correlations. Because the theoretical understanding of strong correlations is still evolving, the review is focused on the analysis of the universal trends that are emerging out of a large body of experimental data augmented where possible with insights from numerical studies.
668 citations
TL;DR: It is demonstrated that the use of plasmonic contact electrodes can significantly mitigate the low-quantum efficiency performance of photoconductive terahertz optoelectronics.
Abstract: For terahertz optoelectronics to find broader applications, more efficient sources and detectors are needed. Towards this end, Berry et al. demonstrate the use of plasmonic contact electrodes for both terahertz emitters and detectors, finding large enhancement over standard photoconductive devices.
480 citations
TL;DR: In this article, the main types and mechanisms of magnetoelectric interactions and conditions of their origin are discussed, as well as potentially practical materials that display magneto-lectric properties at room temperature.
Abstract: The last decade has witnessed a significant growth of research into materials with coupled magnetic and electric properties. Reviewed here are the main types and mechanisms of magnetoelectric interactions and conditions of their origin. Special attention is given to potentially practical materials that display magnetoelectric properties at room temperature. Example applications of magnetoelectric materials and multiferroics in information and energy saving technologies are discussed.
477 citations