Fermi Surface Study Of An Organic Superconductor θ- (Bedt-Ttf)2I3

1993 ◽  
Vol 328 ◽  
Author(s):  
M. Tamura ◽  
H. Kuroda ◽  
S. Uji ◽  
H. Aoki ◽  
M. Tokumoto ◽  
...  
Keyword(s):  
Fermi Surface ◽  
Field Dependence ◽  
Reflectance Spectra ◽  
Organic Superconductor ◽  
Infrared Reflectance ◽  
Magnetic Breakdown ◽  
Surface Study ◽  
Fast Oscillations

ABSTRACTThe temperature and field dependence of the de Haas-van Alphen oscillations in θ- (BEDT-TTF)2l3 is analyzed. The cyclotron masses are estimated to be 2.0 Me and 3.6 me for slow and fast oscillations, respectively. The indication of magnetic breakdown effect is discussed in terms of the geometry of the Fermi surface. The results are compared with those of the infrared reflectance spectra.

scholarly journals Mineral Physicochemistry Underlying Feature-Based Extraction of Mineral Abundance and Composition from Shortwave, Mid and Thermal Infrared Reflectance Spectra

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 347
Author(s):  
Carsten Laukamp ◽  
Andrew Rodger ◽  
Monica LeGras ◽  
Heta Lampinen ◽  
Ian C. Lau ◽  
...  
Keyword(s):  
Mineral Exploration ◽  
Relevant Information ◽  
Ore Deposits ◽  
Reflectance Spectra ◽  
Full Potential ◽  
Infrared Reflectance ◽  
Vibrational Modes ◽  
Diagnostic Features ◽  
Wide Range ◽  
Mineral Assemblages

Reflectance spectroscopy allows cost-effective and rapid mineral characterisation, addressing mineral exploration and mining challenges. Shortwave (SWIR), mid (MIR) and thermal (TIR) infrared reflectance spectra are collected in a wide range of environments and scales, with instrumentation ranging from spaceborne, airborne, field and drill core sensors to IR microscopy. However, interpretation of reflectance spectra is, due to the abundance of potential vibrational modes in mineral assemblages, non-trivial and requires a thorough understanding of the potential factors contributing to the reflectance spectra. In order to close the gap between understanding mineral-diagnostic absorption features and efficient interpretation of reflectance spectra, an up-to-date overview of major vibrational modes of rock-forming minerals in the SWIR, MIR and TIR is provided. A series of scripts are proposed that allow the extraction of the relative intensity or wavelength position of single absorption and other mineral-diagnostic features. Binary discrimination diagrams can assist in rapidly evaluating mineral assemblages, and relative abundance and chemical composition of key vector minerals, in hydrothermal ore deposits. The aim of this contribution is to make geologically relevant information more easily extractable from reflectance spectra, enabling the mineral resources and geoscience communities to realise the full potential of hyperspectral sensing technologies.

scholarly journals Short-range structure, the role of bismuth and property-structure correlations in bismuth borate glasses

2021 ◽  
Author(s):  
Christos P.E. Varsamis ◽  
Nikos Makris ◽  
Christina Valvi ◽  
E. I. Kamitsos
Keyword(s):  
Short Range ◽  
Composition Range ◽  
Reflectance Spectra ◽  
Borate Glasses ◽  
Infrared Reflectance ◽  
Bismuth Borate ◽  
Splat Quenching ◽  
Structure Correlations ◽  
Short Range Structure

Bismuth-containing borate glasses, xBi2O3-(1-x)B2O3, were synthesized in the broad composition range 0.20≤x≤0.80 by melting in Pt crucibles and splat-quenching between two metal blocks. Infrared reflectance spectra, measured in the range...

Effects of Particle Size on the Near-Infrared Reflectance Spectra of Wheat and Rape Seed Meal Mixtures

1995 ◽  
Vol 49 (1) ◽  
pp. 84-91 ◽  
Author(s):  
Marie-Françoise Devaux ◽  
Nathalie Nathier-Dufour ◽  
Paul Robert ◽  
Dominique Bertrand
Keyword(s):  
Particle Size ◽  
Near Infrared ◽  
Reflectance Spectra ◽  
Seed Meal ◽  
Infrared Reflectance ◽  
Rape Seed ◽  
Near Infrared Reflectance

A classical oscillators model for infrared reflectance spectra of Zn3P2

1994 ◽  
Vol 35 (6) ◽  
pp. 775-779 ◽  
Author(s):  
J. Misiewicz ◽  
A. Lemiec ◽  
K. Jezierski ◽  
J.M. Wróbel ◽  
B.P. Clayman
Keyword(s):  
Reflectance Spectra ◽  
Infrared Reflectance

The de Haas–van Alphen effect in alkali metals

1964 ◽  
Vol 281 (1384) ◽  
pp. 62-91 ◽  
Keyword(s):  
Fermi Surface ◽  
Field Dependence ◽  
Alkali Metals ◽  
Spherical Shape ◽  
Orientation Dependence ◽  
Sodium Potassium ◽  
Fermi Surfaces ◽  
Fixed Orientation ◽  
Absolute Amplitude ◽  
Structure Calculations

A new method for studying the de Haas–van Alphen effect in steady magnetic fields has been developed in which the field is modulated at frequency ω and a signal at frequency 2 ω is generated in a pick-up coil round the specimen because of the non-linear field dependence of magnetization. The rectified 2 ω signal is proportional to d 2 M /dH 2 and so shows de Haas–van Alphen oscillations either when H is varied for fixed orientation or when the orientation is varied in fixed H if the Fermi surface is anisotropic. Because the phase of oscillation is very high (of order 10 4 π ) even very slight anisotropy will produce a few oscillations when the orientation is varied and the method is therefore particularly sensitive for studying very nearly spherical Fermi surfaces. From the oscillations with H , values of the frequency F were found for sodium, potassium, rubidium and caesium which were close to those predicted for a free-electron sphere containing 1 electron per atom, though some small systematic deviations of order ½ % were observed which may be significant. From detailed study of the oscillations produced by rotation of single crystals in fixed H it was found possible to describe the orientation dependence of F (proportional to the area of cross-section of the Fermi surface) for potassium and rubidium consistently by a series of cubic harmonics and hence to deduce the small departures of the Fermi surfaces from spherical shape. The deviations from a sphere were found to be of the order of 1 part in 10 3 for potassium and a little less than 1 part in 10 2 for rubidium; these deviations are compared with those predicted by band structure calculations. Preliminary results for sodium suggest that it is appreciably less anisotropic than potassium. Some results are also reported on the temperature and field dependence and the absolute amplitude of the de Haas-van Alphen effect, and it is also shown how the effect can be used to measure very small variations of field with position.

Magnetic oscillations in β″-(BEDT–TTF)4(NH4)[Fe(C2O4)3]·DMF: Fermi surface study and frequency mixing

2004 ◽  
Vol 346-347 ◽  
pp. 359-362
Author(s):  
V.N. Laukhin ◽  
A. Audouard ◽  
L. Brossard ◽  
T.G. Prokhorova ◽  
E.B. Yagubskii ◽  
...  
Keyword(s):  
Fermi Surface ◽  
Surface Study ◽  
Magnetic Oscillations ◽  
Frequency Mixing
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