For determining the efficiency of a monochromator used in vacuum ultraviolet spectroscopy measurements of electron cyclotron resonance generated plasmas at the Ruhr-Universitat Bochum, two different ...methods for absolute and six methods for relative calibrations were used. The results of all relative calibrations except for one agree to within an accuracy close to the experimental error in the range of their mutual overlap. The accuracies of the relative efficiency curves were found to be 18, 14, 7, 3, 6 and 10% for the ranges 110-120, 120-140, 140-250, 250-350, 350-400 and 400-450 nm, respectively. Absolute calibrations were performed at 147 and 364 plus or minus 2 nm with an accuracy of 8% in both cases. (Abstract quotes from original text)
Raman Spectroscopy and Structure of InBO3 Voron'ko, Yu. K.; Dzhurinskii, B. F.; Kokh, A. E. ...
Inorganic materials,
9/2005, Letnik:
41, Številka:
9
Journal Article
Electronic correlation is believed to play an important role in exotic phenomena such as insulator-metal transition, colossal magneto resistance and high temperature superconductivity in correlated ...electron systems. Recently, it has been shown that electronic correlation may also be responsible for the formation of unconventional plasmons. Herewith, using a combination of angle-dependent spectroscopic ellipsometry, angle resolved photoemission spectroscopy and Hall measurements all as a function of temperature supported by first-principles calculations, the existence of low-loss high-energy correlated plasmons accompanied by spectral weight transfer, a fingerprint of electronic correlation, in topological insulator (Bi\(_{0.8}\)Sb\(_{0.2}\))\(_2\)Se\(_3\) is revealed. Upon cooling, the density of free charge carriers in the surface states decreases whereas those in the bulk states increase, and that the newly-discovered correlated plasmons are key to explaining this phenomenon. Our result shows the importance of electronic correlation in determining new correlated plasmons and opens a new path in engineering plasmonic-based topologically-insulating devices.
Quantum states of matter combining non-trivial topology and magnetism attract a lot of attention nowadays; the special focus is on magnetic topological insulators (MTIs) featuring quantum anomalous ...Hall and axion insulator phases. Feasibility of many novel phenomena that \emph{intrinsic} magnetic TIs may host depends crucially on our ability to engineer and efficiently tune their electronic and magnetic structures. Here, using angle- and spin-resolved photoemission spectroscopy along with \emph{ab initio} calculations we report on a large family of intrinsic magnetic TIs in the homologous series of the van der Waals compounds (MnBi\(_2\)Te\(_4\))(Bi\(_2\)Te\(_3\))\(_m\) with \(m=0, ..., 6\). Magnetic, electronic and, consequently, topological properties of these materials depend strongly on the \(m\) value and are thus highly tunable. The antiferromagnetic (AFM) coupling between the neighboring Mn layers strongly weakens on moving from MnBi2Te4 (m=0) to MnBi4Te7 (m=1), changes to ferromagnetic (FM) one in MnBi6Te10 (m=2) and disappears with further increase in m. In this way, the AFM and FM TI states are respectively realized in the \(m=0,1\) and \(m=2\) cases, while for \(m \ge 3\) a novel and hitherto-unknown topologically-nontrivial phase arises, in which below the corresponding critical temperature the magnetizations of the non-interacting 2D ferromagnets, formed by the \MBT\, building blocks, are disordered along the third direction. The variety of intrinsic magnetic TI phases in (MnBi\(_2\)Te\(_4\))(Bi\(_2\)Te\(_3\))\(_m\) allows efficient engineering of functional van der Waals heterostructures for topological quantum computation, as well as antiferromagnetic and 2D spintronics.
An investigation was made of the lasing characteristics of a BBO-crystal Type-I optical parametric oscillator pumped by the 4th harmonic of a multimode Nd:YAG laser. The output was tunable over the ...range 300 - 2340 nm. The efficiency ranged up to 15% near the peak of the tunability curve at double the oscillation threshold. (nonlinear optical phenomena and devices)
Stability of (0001) Bi2Te3 surface Makarenko, S. V.; Atuchin, V. V.; Kokh, K. A. ...
2011 International Conference and Seminar on Micro/Nanotechnologies and Electron Devices Proceedings,
2011-June
Conference Proceeding
The surface stability of single crystals Bi 2 Se 3 and Bi 2 Te 3 has been studied by XPS, AFM, STM and RHEED techniques. The Bi 2 Se 3 and Bi 2 Te 3 single crystals were grown by vertical Bridgman ...method. Crystal cleaving induced atomically flat surfaces over 1 cm 2 area. XPS revealed that cleaved Bi 2 Se 3 and Bi 2 Te 3 surface were stable to oxidation over two months. The surfaces are sufficiently inert to obtain STM atomic resolution even in two weeks after cleaved.
