The de Haas–van Alphen effect in rhodium

1966 ◽  
Vol 295 (1443) ◽  
pp. 458-475 ◽  
Keyword(s):  
Simple Model ◽  
Band Structure ◽  
Fermi Surface ◽  
Fermi Level ◽  
Noise Level ◽  
Field Method ◽  
Band Model ◽  
Wide Range ◽  
The Many ◽  
Cyclotron Mass

The pulsed field method has been used to study the de Haas–van Alphen effect in rhodium. Using suitable filtering techniques it was possible to separate and measure over a wide range of field orientations the many frequencies present. From the data several separate sheets of Fermi surface could be identified and their dimensions determined with little ambiguity. These dimensions are compared with a Fermi surface predicted by assuming the band structure of rhodium to be like that theoretically predicted for nickel but choosing the Fermi level to agree with the different number of electrons in rhodium. This model explains satisfactorily all the frequencies observed and explains why several additional frequencies that have not been observed are below the noise level. The behaviour of the transverse magnetoresistance of rhodium is predicted and this could be used for a further test of the correctness of the model. Those values of cyclotron mass that have been measured, although necessarily only roughly, disagree significantly with this simple model but a more satisfactory agreement is obtained by considering a ‘semi rigid band model' in which the width of the d bands varies from metal to metal. If the d bands in rhodium are assumed to be of order twice the width of those in nickel both the dimensions of the Fermi surface and the cyclotron masses can be satisfactorily explained.

scholarly journals An ab-initio study on structural, elastic, electronic, bonding, thermal, and optical properties of topological Weyl semimetal TaX (X = P, As)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
M. I. Naher ◽  
S. H. Naqib
Keyword(s):  
Optical Properties ◽  
Band Structure ◽  
Fermi Level ◽  
Density Of States ◽  
Electronic Band Structure ◽  
Optical Parameters ◽  
Electronic Density ◽  
Electronic Band ◽  
Wide Range ◽  
Weyl Semimetals

AbstractIn recent days, study of topological Weyl semimetals have become an active branch of physics and materials science because they led to realization of the Weyl fermions and exhibited protected Fermi arc surface states. Therefore, topological Weyl semimetals TaX (X = P, As) are important electronic systems to investigate both from the point of view of fundamental physics and potential applications. In this work, we have studied the structural, elastic, mechanical, electronic, bonding, acoustic, thermal and optical properties of TaX (X = P, As) in detail via first-principles method using the density functional theory. A comprehensive study of elastic constants and moduli shows that both TaP and TaAs possesses low to medium level of elastic anisotropy (depending on the measure), reasonably good machinability, mixed bonding characteristics with ionic and covalent contributions, brittle nature and relatively high Vickers hardness with a low Debye temperature and melting temperature. The minimum thermal conductivities and anisotropies of TaX (X = P, As) are calculated. Bond population analysis supports the bonding nature as predicted by the elastic parameters. The bulk electronic band structure calculations reveal clear semi-metallic features with quasi-linear energy dispersions in certain sections of the Brillouin zone near the Fermi level. A pseudogap in the electronic energy density of states at the Fermi level separating the bonding and the antibonding states indicates significant electronic stability of tetragonal TaX (X = P, As).The reflectivity spectra show almost non-selective behavior over a wide range of photon energy encompassing visible to mid-ultraviolet regions. High reflectivity over wide spectral range makes TaX suitable as reflecting coating. TaX (X = P, As) are very efficient absorber of ultraviolet radiation. Both the compounds are moderately optically anisotropic owing to the anisotropic nature of the electronic band structure. The refractive indices are very high in the infrared to visible range. All the energy dependent optical parameters show metallic features and are in complete accord with the underlying bulk electronic density of states calculations.

Investigation of the valence band structure of PbSe by optical and transport measurement

2013 ◽  
Vol 1490 ◽  
pp. 75-81 ◽  
Author(s):  
Thomas C. Chasapis ◽  
Yeseul Lee ◽  
Georgios S. Polymeris ◽  
Eleni C. Stefanaki ◽  
Euripides Hatzikraniotis ◽  
...  
Keyword(s):  
Band Structure ◽  
Valence Band ◽  
Room Temperature ◽  
Heavy Hole ◽  
Light Hole ◽  
Band Model ◽  
Valence Band Structure ◽  
Effective Masses ◽  
Wide Range ◽  
Two Band Model

ABSTRACTWe investigated the valence band structure of PbSe by a combined study of the optical and transport properties of p-type Pb1-xNaxSe, with Na concentrations ranging from 0 – 4%, yielding carrier densities in a wide range of 1018 – 1020 cm−3. Room temperature infrared reflectivity studies showed that the susceptibility (or conductivity) effective mass m* increases from ∼ 0.06mo to ∼ 0.5mo on increasing Na content from 0.08% to 3%. The Seebeck coefficient scales with doping in the whole temperature range, yielding lower values for higher Na contents, while the Hall coefficient increases on heating from room temperature showing a peak close to 650 K. The room temperature Pisarenko plot is well described by the simple parabolic band model up to ∼ 1·1020 cm−3. In order to describe the behaviour in the whole concentration range, the application of the two band model, i.e. light hole and heavy hole, was used giving density of states effective masses 0.28mo and 2.5mo for the two bands respectively.

Topology of the fermi surface and band structure near the fermi level in the Pb-doped Bi2Sr2CuO6+δ superconductor

2001 ◽  
Vol 114-116 ◽  
pp. 629-634 ◽  
Author(s):  
T. Takeuchi ◽  
T. Yokoya ◽  
S. Shin ◽  
K. Jinno ◽  
M. Matsuura ◽  
...  
Keyword(s):  
Band Structure ◽  
Fermi Surface ◽  
Fermi Level

Discussion of the band structure effects on thermoemission as deduced from a simple model

1976 ◽  
Vol 37 (2) ◽  
pp. 149-158 ◽  
Author(s):  
A.K. Bhattacharjee ◽  
B. Caroli ◽  
D. Saint-James
Keyword(s):  
Simple Model ◽  
Band Structure

The Many Pasts of Detective Fiction

2020 ◽  
Vol 1 (2) ◽  
pp. 157-172
Author(s):  
Thomas Leitch
Keyword(s):  
Detective Fiction ◽  
Golden Age ◽  
Public History ◽  
Detective Novel ◽  
Sherlock Holmes ◽  
Detective Story ◽  
The Past ◽  
Wide Range ◽  
Detective Novels ◽  
The Many

Building on Tzvetan Todorov's observation that the detective novel ‘contains not one but two stories: the story of the crime and the story of the investigation’, this essay argues that detective novels display a remarkably wide range of attitudes toward the several pasts they represent: the pasts of the crime, the community, the criminal, the detective, and public history. It traces a series of defining shifts in these attitudes through the evolution of five distinct subgenres of detective fiction: exploits of a Great Detective like Sherlock Holmes, Golden Age whodunits that pose as intellectual puzzles to be solved, hardboiled stories that invoke a distant past that the present both breaks with and echoes, police procedurals that unfold in an indefinitely extended present, and historical mysteries that nostalgically fetishize the past. It concludes with a brief consideration of genre readers’ own ambivalent phenomenological investment in the past, present, and future each detective story projects.

Effect of proximity of the Fermi level to singular points in the band structure on the kinetic and lattice properties of metals and alloys

1988 ◽  
Vol 154 (3) ◽  
pp. 525 ◽  
Author(s):  
V.P. Antropov ◽  
Valentin G. Vaks ◽  
M.I. Katsnel'son ◽  
V.G. Koreshkov ◽  
A.I. Likhtenshtein ◽  
...  
Keyword(s):  
Band Structure ◽  
Fermi Level ◽  
Metals And Alloys ◽  
Singular Points

Ab initio calculation on the Optical Properties of AA- Stacked two dimensional Graphene, Silicene, Germanene, and Stanene

2018 ◽  
Vol 1 (1) ◽  
pp. 46-50
Author(s):  
Rita John ◽  
Benita Merlin
Keyword(s):  
Optical Properties ◽  
Band Structure ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Complex Refractive Index ◽  
Single Layer ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Wide Range ◽  
Optical Region

In this study, we have analyzed the electronic band structure and optical properties of AA-stacked bilayer graphene and its 2D analogues and compared the results with single layers. The calculations have been done using Density Functional Theory with Generalized Gradient Approximation as exchange correlation potential as in CASTEP. The study on electronic band structure shows the splitting of valence and conduction bands. A band gap of 0.342eV in graphene and an infinitesimally small gap in other 2D materials are generated. Similar to a single layer, AA-stacked bilayer materials also exhibit excellent optical properties throughout the optical region from infrared to ultraviolet. Optical properties are studied along both parallel (||) and perpendicular ( ) polarization directions. The complex dielectric function (ε) and the complex refractive index (N) are calculated. The calculated values of ε and N enable us to analyze optical absorption, reflectivity, conductivity, and the electron loss function. Inferences from the study of optical properties are presented. In general the optical properties are found to be enhanced compared to its corresponding single layer. The further study brings out greater inferences towards their direct application in the optical industry through a wide range of the optical spectrum.

Textual Transformations

2019 ◽  
Keyword(s):  
Early Modern ◽  
Financial Incentives ◽  
Book History ◽  
John Dryden ◽  
Book Production ◽  
Original Essays ◽  
Wide Range ◽  
Lucy Hutchinson ◽  
The Many ◽  
The Impact

This collection of twelve original essays by an international team of eminent scholars in the field of book history explores the many ways in which early modern books were subject to reworking, re-presentation, revision and reinterpretation. Their history is often the history of multiple, sometimes competing, agencies as their texts were re-packaged, redirected and transformed in ways that their original authors might hardly recognize. The essays discuss the processes of editing, revision, redaction, selection, abridgement, glossing, disputation, translation and posthumous publication that resulted in a textual elasticity and mobility that could dissolve distinctions between text and paratexts, textuality and intertextuality, manuscript and print, author and reader or editor, such that title and author’s name are no longer sufficient pointers to a book’s identity or contents. The essays are alive to the impact of commercial and technological aspects of book production and distribution (discussing, for example, the career of the pre-eminent bookseller John Nourse, the market appeal of abridgements, and the financial incentives to posthumous publication), but their interest is also in the many additional forms of agency that shaped texts and their meanings as books were repurposed to articulate, and respond to, a variety of cultural and individual needs. They engage with early modern religious, political, philosophical and scholarly trends and debates as they discuss a wide range of genres and kinds of publication (including fictional and non-fictional prose, verse miscellanies, abridgements, sermons, religious controversy) and of authors and booksellers (including Lucy Hutchinson, Richard Baxter, Thomas Burnet, Elizabeth Rowe, John Dryden, and Samuel Taylor Coleridge, Lucy Hutchinson, Henry Maundrell, John Nourse; Jonathan Swift, Samuel Richardson, John Tillotson, Isaac Watts and John Wesley).

Using Motion Detection to Measure Social Polarization in the U.S. House of Representatives

2020 ◽  
pp. 1-10
Author(s):  
Bryce J. Dietrich
Keyword(s):  
Motion Detection ◽  
House Of Representatives ◽  
Social Science Research ◽  
Image Data ◽  
Science Research ◽  
Video Data ◽  
Social Scientists ◽  
Wide Range ◽  
Party Voting ◽  
The Many

Abstract Although previous scholars have used image data to answer important political science questions, less attention has been paid to video-based measures. In this study, I use motion detection to understand the extent to which members of Congress (MCs) literally cross the aisle, but motion detection can be used to study a wide range of political phenomena, like protests, political speeches, campaign events, or oral arguments. I find not only are Democrats and Republicans less willing to literally cross the aisle, but this behavior is also predictive of future party voting, even when previous party voting is included as a control. However, this is one of the many ways motion detection can be used by social scientists. In this way, the present study is not the end, but the beginning of an important new line of research in which video data is more actively used in social science research.

scholarly journals Restructured single parabolic band model for quick analysis in thermoelectricity

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Jianbo Zhu ◽  
Xuemei Zhang ◽  
Muchun Guo ◽  
Jingyu Li ◽  
Jinsuo Hu ◽  
...  
Keyword(s):  
Fermi Level ◽  
Carrier Concentration ◽  
Carrier Mobility ◽  
Optimization Design ◽  
State Of The Art ◽  
Band Model ◽  
Carrier Effective Mass ◽  
Intermediate Variables ◽  
Level Calculation ◽  
Spb Model

AbstractThe single parabolic band (SPB) model has been widely used to preliminarily elucidate inherent transport behaviors of thermoelectric (TE) materials, such as their band structure and electronic thermal conductivity, etc. However, in the SPB calculation, it is necessary to determine some intermediate variables, such as Fermi level or the complex Fermi-Dirac integrals. In this work, we establish a direct carrier-concentration-dependent restructured SPB model, which eliminates Fermi-Dirac integrals and Fermi level calculation and emerges stronger visibility and usability in experiments. We have verified the reliability of such restructured model with 490 groups of experimental data from state-of-the-art TE materials and the relative error is less than 2%. Moreover, carrier effective mass, intrinsic carrier mobility and optimal carrier concentration of these materials are systematically investigated. We believe that our work can provide more convenience and accuracy for thermoelectric data analysis as well as instructive understanding on future optimization design.

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