Fermi Surface Study of Organic Metals (Bedt-TTF)2X

1992 ◽  
Vol 247 ◽  
Author(s):  
M. Tokumoto ◽  
A. G. Swanson ◽  
J. S. Brooks ◽  
C. C. Agosta ◽  
S. T. Hannahs ◽  
...  
Keyword(s):  
Fermi Surface ◽  
Fundamental Frequency ◽  
Electronic System ◽  
Surface Topology ◽  
Spin Splitting ◽  
Simple Metal ◽  
Organic Metals ◽  
Fundamental Frequencies ◽  
First Time ◽  
Oscillation Characteristic

ABSTRACTObservations of Shubnikov-de Haas(SdH) and de Haas-van Alphen(dHvA) oscillations in organic metals (BEDT-TTF)2X, with X=KHg(SCN)4, θ-I3 and β″-AuBr2. are reported. In KHg(SCN)4 salt, in addition to the SdH oscillations with fundamental frequency of 670 T corresponding to about 16% of the first Brillouin zone(FBZ), we observed splitting of each SdH peak which we ascribed to “spin-splitting” We have also found that the ground state of this salt is not a simple metal but has some magnetic character. In θ-l3 salt we have succeeded in an observation of dHvA oscillations for the first time. We observed a “saw-tooth” dHvA oscillation characteristic to a highly two-dimensional and extraordinary clean electronic system. In addition to the fundamental frequency of 4170 T corresponding to 50.4 % of the FBZ and its higher harmonics, we observed an oscillation with lower frequency of 730 T corresponding to about 8.8 % of the FBZ. A new Fermi surface topology for θ-l3 salt is proposed based on the analysis of the dHvA effect. In β″-AuBr2, we observed complex dHvA oscillations, which can be explained in terms of the mixing of two fundamental frequencies of 47 and 268 T, suggesting the presence of very small pockets corresponding to 0.6 and 2.9 % of the FBZ.

scholarly journals Fermi surface and kink structures in $$\hbox {Sr}_{{4}}\hbox {Ru}_{{3}}\hbox {O}_{{10}}$$ revealed by synchrotron-based ARPES

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Prosper Ngabonziza ◽  
Emanuela Carleschi ◽  
Volodymyr Zabolotnyy ◽  
Amina Taleb-Ibrahimi ◽  
François Bertran ◽  
...  
Keyword(s):  
Fermi Surface ◽  
Fermi Level ◽  
Surface Topology ◽  
Photon Polarization ◽  
Strong Electron ◽  
Electron Phonon Coupling ◽  
Band Dispersion ◽  
Lattice Dynamic Calculation ◽  
First Time ◽  
O 10

AbstractThe low-energy electronic structure, including the Fermi surface topology, of the itinerant metamagnet $$\hbox {Sr}_{{4}}\hbox {Ru}_{{3}}\hbox {O}_{{10}}$$ Sr 4 Ru 3 O 10 is investigated for the first time by synchrotron-based angle-resolved photoemission. Well-defined quasiparticle band dispersions with matrix element dependencies on photon energy or photon polarization are presented. Four bands crossing the Fermi-level, giving rise to four Fermi surface sheets are resolved; and their complete topography, effective mass as well as their electron and hole character are determined. These data reveal the presence of kink structures in the near-Fermi-level band dispersion, with energies ranging from 30 to 69 meV. Together with previously reported Raman spectroscopy and lattice dynamic calculation studies, the data suggest that these kinks originate from strong electron–phonon coupling present in $$\hbox {Sr}_{{4}}\hbox {Ru}_{{3}}\hbox {O}_{{10}}$$ Sr 4 Ru 3 O 10 . Considering that the kink structures of $$\hbox {Sr}_{{4}}\hbox {Ru}_{{3}}\hbox {O}_{{10}}$$ Sr 4 Ru 3 O 10 are similar to those of the other three members of the Ruddlesden Popper structured ruthenates, the possible universality of strong coupling of electrons to oxygen-related phonons in $$\hbox {Sr}_{n+1}\hbox {Ru}_{{n}}\hbox {O}_{3n+1}$$ Sr n + 1 Ru n O 3 n + 1 compounds is proposed.

A Tape Striation Counting Method for Determining Fundamental Frequency

1979 ◽  
Vol 10 (4) ◽  
pp. 246-248 ◽  
Author(s):  
Peter B. Mueller ◽  
Marla Adams ◽  
Jean Baehr-Rouse ◽  
Debbie Boos
Keyword(s):  
Fundamental Frequency ◽  
Counting Method ◽  
Male And Female ◽  
Fundamental Frequencies ◽  
Counting Procedure ◽  
Female Subjects

Mean fundamental frequencies of male and female subjects obtained with FLORIDA I and a tape striation counting procedure were compared. The fundamental frequencies obtained with these two methods were similar and it appears that the tape striation counting procedure is a viable, simple, and inexpensive alternative to more costly and complicated procedures and instrumentation.

scholarly journals Ultrafast dynamical Lifshitz transition

2021 ◽  
Vol 7 (17) ◽  
pp. eabd9275
Author(s):  
Samuel Beaulieu ◽  
Shuo Dong ◽  
Nicolas Tancogne-Dejean ◽  
Maciej Dendzik ◽  
Tommaso Pincelli ◽  
...  
Keyword(s):  
Fermi Surface ◽  
Colossal Magnetoresistance ◽  
Surface Topology ◽  
Strongly Correlated ◽  
Many Body ◽  
Time Resolved ◽  
Weyl Semimetal ◽  
Lifshitz Transition ◽  
Fermi Surface Topology ◽  
Many Body Systems

Fermi surface is at the heart of our understanding of metals and strongly correlated many-body systems. An abrupt change in the Fermi surface topology, also called Lifshitz transition, can lead to the emergence of fascinating phenomena like colossal magnetoresistance and superconductivity. While Lifshitz transitions have been demonstrated for a broad range of materials by equilibrium tuning of macroscopic parameters such as strain, doping, pressure, and temperature, a nonequilibrium dynamical route toward ultrafast modification of the Fermi surface topology has not been experimentally demonstrated. Combining time-resolved multidimensional photoemission spectroscopy with state-of-the-art TDDFT+U simulations, we introduce a scheme for driving an ultrafast Lifshitz transition in the correlated type-II Weyl semimetal Td-MoTe2. We demonstrate that this nonequilibrium topological electronic transition finds its microscopic origin in the dynamical modification of the effective electronic correlations. These results shed light on a previously unexplored ultrafast scheme for controlling the Fermi surface topology in correlated quantum materials.

The Influence of Support Hardware and Piping System Seismic Response on Snubber Support Damping

1997 ◽  
Vol 119 (4) ◽  
pp. 451-456 ◽  
Author(s):  
C. Lay ◽  
O. A. Abu-Yasein ◽  
M. A. Pickett ◽  
J. Madia ◽  
S. K. Sinha
Keyword(s):  
Seismic Response ◽  
Fundamental Frequency ◽  
Damping Ratio ◽  
Damping Coefficient ◽  
Piping System ◽  
Nodal Displacement ◽  
Damping Coefficients ◽  
Fundamental Frequencies ◽  
Piping Systems

The damping coefficients and ratios of piping system snubber supports were found to vary logarithmically with pipe support nodal displacement. For piping systems with fundamental frequencies in the range of 0.6 to 6.6 Hz, the support damping ratio for snubber supports was found to increase with increasing fundamental frequency. For 3-kip snubbers, damping coefficient and damping ratio decreased logarithmically with nodal displacement, indicating that the 3-kip snubbers studied behaved essentially as coulomb dampers; while for the 10-kip snubbers studied, damping coefficient and damping ratio increased logarithmically with nodal displacement.

Pressure-induced change of the Fermi surface topology in Al-based solid solutions

2003 ◽  
Vol 45 (12) ◽  
pp. 2213-2217 ◽  
Author(s):  
A. S. Mikhailushkin ◽  
É. I. Isaev ◽  
Yu. Kh. Vekilov ◽  
S. I. Simak
Keyword(s):  
Fermi Surface ◽  
Solid Solutions ◽  
Surface Topology ◽  
Fermi Surface Topology

scholarly journals Fermi surface topology and large magnetoresistance in the topological semimetal candidate PrBi

2019 ◽  
Vol 99 (24) ◽  
Author(s):  
Amit Vashist ◽  
R. K. Gopal ◽  
Divya Srivastava ◽  
M. Karppinen ◽  
Yogesh Singh
Keyword(s):  
Fermi Surface ◽  
Surface Topology ◽  
Topological Semimetal ◽  
Fermi Surface Topology

scholarly journals Transport signatures of Fermi surface topology change in BiTeI

2015 ◽  
Vol 91 (20) ◽  
Author(s):  
Linda Ye ◽  
Joseph G. Checkelsky ◽  
Fumitaka Kagawa ◽  
Yoshinori Tokura
Keyword(s):  
Fermi Surface ◽  
Surface Topology ◽  
Topology Change ◽  
Fermi Surface Topology

scholarly journals Fermi-surface topology of the heavy-fermion system Ce2PtIn8

2018 ◽  
Vol 97 (16) ◽  
Author(s):  
J. Klotz ◽  
K. Götze ◽  
E. L. Green ◽  
A. Demuer ◽  
H. Shishido ◽  
...  
Keyword(s):  
Fermi Surface ◽  
Heavy Fermion ◽  
Surface Topology ◽  
Fermion System ◽  
Heavy Fermion System ◽  
Fermi Surface Topology

Phonetics of Singing in Western Classical Style

2018 ◽  
Author(s):  
Johan Sundberg
Keyword(s):  
Fundamental Frequency ◽  
Vocal Fold ◽  
Vocal Tract ◽  
Formant Frequency ◽  
Vowel Identification ◽  
Fundamental Frequencies ◽  
Vocal Fold Vibration ◽  
Syllable Duration ◽  
Classical Singing ◽  
The Voice

The function of the voice organ is basically the same in classical singing as in speech. However, loud orchestral accompaniment has necessitated the use of the voice in an economical way. As a consequence, the vowel sounds tend to deviate considerably from those in speech. Male voices cluster formant three, four, and five, so that a marked peak is produced in spectrum envelope near 3,000 Hz. This helps them to get heard through a loud orchestral accompaniment. They seem to achieve this effect by widening the lower pharynx, which makes the vowels more centralized than in speech. Singers often sing at fundamental frequencies higher than the normal first formant frequency of the vowel in the lyrics. In such cases they raise the first formant frequency so that it gets somewhat higher than the fundamental frequency. This is achieved by reducing the degree of vocal tract constriction or by widening the lip and jaw openings, constricting the vocal tract in the pharyngeal end and widening it in the mouth. These deviations from speech cause difficulties in vowel identification, particularly at high fundamental frequencies. Actually, vowel identification is almost impossible above 700 Hz (pitch F5). Another great difference between vocal sound produced in speech and the classical singing tradition concerns female voices, which need to reduce the timbral differences between voice registers. Females normally speak in modal or chest register, and the transition to falsetto tends to happen somewhere above 350 Hz. The great timbral differences between these registers are avoided by establishing control over the register function, that is, over the vocal fold vibration characteristics, so that seamless transitions are achieved. In many other respects, there are more or less close similarities between speech and singing. Thus, marking phrase structure, emphasizing important events, and emotional coloring are common principles, which may make vocal artists deviate considerably from the score’s nominal description of fundamental frequency and syllable duration.

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