Electronic Properties Of Solids Research Articles

J.Singleton, Band Theory and Electronic Properties of Solids, Oxford University Press, 2001, xvi+222p., 25×l9cm, \l0,540, (Oxford Master Series in Condensed Matter Physics), [大学院向

J.Singleton, Band Theory and Electronic Properties of Solids, Oxford University Press, 2001, xvi+222p., 25×l9cm, \l0,540, (Oxford Master Series in Condensed Matter Physics), [大学院向

Temperature-induced distortions of electronic states observed via forbidden Bragg reflections in germanium

According to the adiabatic approximation, the electronic states of atoms in solids are bound up with thermal atomic motion. As a result, thermal-motion-induced (TMI) anisotropy of x-ray susceptibility can appear for atoms occupying positions with high symmetry. We report evidence for this effect found in the very strong temperature dependence of the 006 forbidden Bragg reflections from a germanium single crystal. The intensity of these reflections increases or decreases drastically as the temperature rises from 30 K to 300 K, in contrast with nonforbidden reflections. It is found that the TMI anisotropy of the structure amplitude scales with the temperature as the mean square of the atomic displacements. This observation is very important for understanding the intricate interplay between phonon and electronic properties of solids.

A Fully Relativistic Full-Potential LCAO Method for Solids

We present a fully relativistic full-potential linear-combination-of-atomic-orbitals method for solids based on the density-functional theory within the local-density approximation. We solve the Dirac-Kohn-Sham equations directly, handling not only the indirect relativistic effect but also the effect due to the spin-orbit coupling self-consistently. We apply the present method to Au and InSb and compare the results with those of experimental and other theoretical studies. Consequently, we show that the agreement is good and the present method is capable of obtaining reliable results in studying the structural and electronic properties of solids.

Exchange and correlation interactions and band structure of non-close-packed solids

The electronic properties of solids are calculated by the Green’s function method taking account of the deformation of the atomic spheres to atomic ellipsoids by the crystal field. It is shown that the ratio of the correlation and exchange interactions in the crystal influences the nature of the band structure in non-close-packed solids.

A Full-Potential Local-Orbital Approach to the Density-Functional Calculations of Solids

A full-potential linear-combination-of-atomic-orbitals method based on the density-functional theory developed in the field of the molecular science is extended to the density-functional calculations of solids. It is shown that the method is also useful for studying both the structural and electronic properties of solids. The interatomic distances of graphite and hexagonal boron nitride are calculated within the error of less than 1%. Also, the atomization energies and the elastic constants are properly reproduced by the present method.

NANOWIRES ON STEPPED METAL SURFACES

The electronic properties of solids can be tailored by structuring them on the nanometer scale. Such a program is becoming reality as surface analysis techniques and sophisticated growth methods are merging. Here, we present results of a venture into one-dimensional nanostructures, grown by decoration of steps at metal surfaces. The growth modes and electronic states are studied using scanning tunneling microscopy (STM) and inverse photoemission. Two-dimensional analogs of Stranski–Krastanov and layer-by-layer growth are found for Cu on stepped Mo(110) and W(110), respectively. Contrast between different metals is achieved in STM pictures by resonant tunneling via surface states and image states, with the latter providing a map of the work function. The limit of single atomic rows decorating step edges is studied by inverse photoemission, and an energy shift of 0.4 eV is found for electronic states of step atoms. Stripe structures are attractive for the study of two- versus one-dimensional magnetism, for magnetoresistive sensors, and in the design of anisotropic materials.

High-pressure studies on semiconductor nanocrystals: size effects in the structural and electronic properties of solids

High-pressure studies on semiconductor nanocrystals: size effects in the structural and electronic properties of solids

Frequency Dependent Conductivity in Organic Superconductors

Abstract Optical studies, in a wide sense, are one of the most powerful techniques for studying the electronic properties of solids. We discuss investigations of the electro dynamic response in the two-dimensional organic conductors of the BEDT-TTF family, which become superconducting at around 10 K. In the normal state, the frequency dependent conductivity is that of a weakly correlated metal with significant deviations from a simple Drude metal. The electro-dynamical properties of the superconducting state are those of an anisotropic, but conventional BCS superconductor.

Atomic forces in the self‐consistent tight‐binding model

AbstractThe self‐consistent tight‐binding (SCTB) model for structural and electronic properties of solids, which can treat both ionicity and covalency on an equal footing, is re‐formulated so as to be applicable to general and disordered systems and is analyzed in comparison with the tight‐binding bond (TBB) model. It is shown that atomic forces in the SCTB model are given very simply as well as in other tight‐binding type theories. Atomic forces consist of three types of contributions, which are those from the interatomic Coulomb interaction, from the covalent energy, and from the overlap repulsion. By using the present formulation, it is possible to calculate quantum‐mechanically the structural and electronic properties of extended defects or disordered systems of sp‐bondod materials with both the properties, ionicity and covalency, which have not yet been treated enough theoretically or quantitatively.

Theory of bulk moduli of hard solids

Two theoretical approache are describes to examine the bulk moduli of solids. The first is based on an ab initio method requiring only the atomic numbers of the constituent atoms as input. The second is a much simpler empirical approach which is applicable to diamond and zinc blende solids and uses the nearest-neighbor bond length as input. Both methods give comparable results, but the inition approach can be used to study the details of the structural, bonding and electronic properties of solids. Thi s aspect of the ab initio method is illustrated by a description of the bonding changes during a graphite-to-diamond pressure-induced transition and by a study of the structural and bonding properties of BN, BP, BAs and SiC.

Gravitationally induced supercurrents in the Schwarzschild field

AbstractUsing the jellium model the behaviour of electronic properties in solids in external gravitational fields is investigated. The charge carriers are influenced by the gravitational field both directly and via the gravitationally induced lattice deformations. As an example we treat London superconductors on circular orbits in the Schwarzschild field of the earth. This motion induces alternating supercurrents with frequencies of the order 0,3 s−1. There exists a general relativistic difference of the oscillation frequencies in different directions. Its relative value is of the order 10−9.

Photoelectronic techniques for material diagnostic

In this paper, the most importnat parameters characterizing the physical properties of electronic materials are briefly analysed. Special attention is given to the intrinsic parameters such as energy gap, density of states and effective masses in the bands, to the extrinsic ones such as energy and concentration of trapping or recombination centers in the forbidden gap, to the carrier lifetimes and surface recombination velocities. The knowledge of all these parameters is very important, since they strongly influence the electronic behaviour of the materials. To this purpose, some of the main electronic and photoelectronic techniques have been selected, which, in our opinion, are particularly suitable to give information about the electronic properties of solids, specially in the case of semiconductor materials. Thus, intrinsic parameters are analysed by the behaviour of resistivity, mobility and carrier concentration as a function of temperature; the extrinsic parameters by techniques such as Space-Charge-Limited-Currents (SCLC), Thermally-Stimulated-Currents (TSC); carrier lifetimes and surface recombination velocities by the spectral response of photoconductivity and photomagnetoelectric effect (PME). The basic physical principles and a short theoretical treatment are given for each method of analysis, together with typical examples of application, indicative of the ranges of validity and sensitivity.

First-principles nonlocal-pseudopotential approach in the density-functional formalism: Development and application to atoms

We present a method for obtaining first-principles nonlocal atomic pseudopotentials in the density-functional formalism by direct inversion of the pseudopotential eigenvalue problem, where the pseudo-wave-functions are represented as a unitary rotation of the exact all-electron wave functions. The usual pseudopotential nonuniqueness of the orbitals is fixed by imposing the physically appealing constraints of maximum similarity to the all-electron wave functions and minimum radial kinetic energy. These potentials are shown to yield very accurate energy eigenvalues, total energy differences, and wave-function moments over a wide range of excited atomic configurations. We have calculated the potentials for 68 transition and nontransition elements of rows 1-5 in the Periodic Table. Their characteristic features, such as classical turning points and minimum potential radii, faithfully reflect the chemical regularities of the Periodic Table. The nonempirical nature of these potentials permits both an analysis of their dominant features in terms of the underlying interelectronic potentials and the systematic improvement of their predictions through inclusion of appropriate correlation terms. As these potentials accurately reproduce both energy eigenvalues and wave functions and can be readily fit to analytic forms with known asymptotic behavior, they can be used directly for studies of many structural and electronic properties of solids (presented in a separate paper).

Electronic Transitions and the High Pressure Chemistry and Physics of Solids

There is no paucity of books on high pressure. Beginning with P. W. Bridgman's The Physics of High Pressure, books of general interest include the two-volume Physics and Chemistry of High Pressure, edited by R. S. Bradley, and the series, Advances in High Pressure Research, as well as the report on the Lake George Conference in 1960. Solid state physics is well represented by Solids Under Pressure, edited by Paul and Warschauer, by Physics of Solids at High Pressure, edited by Tomizuka and Emrick, and by Properties Physiques des Solides sous Pression, edited by Bloch, as well as by chapters in Volumes 6, 13, 17, and 19 of Solid State Physics, edited by Seitz, Turnbull, and Ehrenreich. Chemistry in gases and liquids is covered in Weale's Chemical Reactions at High Pressure, and Hamann's Physico-chemical Effects of Pressure. In addition to the coverage of techniques and calibrations in the above volumes, Modern Very High Pressure Techniques, edited by Wentorf, High Pressure Methods in Solid State Research, by C. C. Bradley, The Accurate Characterization of the High Pressure Environment, edited by E. C. Lloyd, and a chapter in Volume 11 of Solid State Physics are devoted entirely to this facet of high pressure research. It is not our plan either to supersede or extend these approaches. It is our purpose here to discuss the effect of high pressure on the electronic properties of solids.

Festkörperprobleme XIII: Advances in Solid State Physics

H J Queisser (ed) Oxford: Pergamon Press 1973 pp 396 price £13 These two volumes will be reviewed jointly, since they have many common features. Both are collections of invited papers given at two conferences whose subjects overlap to some extent, the first being devoted to devices based on the electronic properties of solids, the second dealing with the physics of solids with some reference to device applications.

Research Using Synchrotron Radiation

In a period of less than ten years, the use of synchrotron radiation in the study of the optical and electronic properties of solids, liquids, and gases has developed from a laboratory curiosity into a widely exploited technique applicable to the needs of investigators working in physics, chemistry, and biology. In this report we discuss the history, present state and future development of this phenomenon in far ultraviolet and soft x-ray research.

Exploring solids with far infrared radiation

Abstract The development of refined experimental techniques in far infrared spectroscopy has resulted in the application of studies in this spectral region to a wide range of solid-state problems. Experimental improvements include the widespread use of interferometric or Fourier techniques, better detectors, and the introduction of far infrared lasers. These are briefly discussed as a prelude to a selection of recent experimental results reflecting various solid-state properties. The vibrational modes of pure and doped crystals have received considerable study, and here attention is focused on the properties of low frequency impurity resonance modes and the tunnelling states of off-centre impurity ions. Developments in the field of resonance in ordered magnetic materials are described, followed by examples of measurements on superconductors. The last two sections deal with various electronic properties of solids which have been probed in the far infrared: the energy levels of impurities and defects, and cyclotron resonance of charge carriers.

The thermocurrents technique: A method for the study of dielectric and electronic properties of solids and liquids

Abstract The principle of the ITC method is discussed in detail and some of its latest applications to solid and liquids dielectrics are summarized.

Electronic and physico-chemical behaviour of some lamellar compounds of graphite

Some comparisons were made between the lamellar crystalline compounds of graphite and intercalary compounds formed of a certain number of other crysthls with shell structure. Although there is a certain number of resemblances, the graphite is almost unique with respect to the amphoteric character of its hexagonal lattices. They can be considered as aromatic macromolecules. In graphite, the interaction between these macromolecules is only weak. They preserve the essence of their aromatic structure in numerous crystalline compounds. Because of the aromatic character there is produced, in a distinct fashion, in the crystulline compounds a charge transfer between these macromolecules and various intercalary groups. This causes profound modifications in the electronic properties of solids. By interposing electron donor groups such as the atoms of an alkali metal or electron acceptor groups such as the halogens or acid radicals, a new class of very conductive solids is obtained. Anisotropic studies of the electrical properties of these solids parallel and perpendicular to the hexagonal layers of the carbon are analyzed. They give important information on the charge transfer to or from aromatic macromolecules. Impurities or crystalline faults of the original graphite modify the formation and the behavior of its crystalline compounds. Some impuritymore » atoms at the edges can facilitate the intercalation of groups in the crystalline compounds and can also affect the electron levels in the macromolecules of carbon, modifying as a result the free bonding energy. Lattice faults can seriously perturb the planeity of aromatic lattices because of the impurity atoms bound to a hold or a prominence of the lattice. Spiral dislocations of the lattice were detected in some graphites. It is unknown to what extent these faults or other faults can affect the conclusions, based on crystalline compounds. (tr-auth)« less

The effect of radiation damage on the electronic properties of solids

An outline is given of the way in which the concentration of defects introduced by irradiation may be estimated. The topics which are discussed are the effects of irradiation on the electron mobility in metals, the carrier concentration in germanium and the optical absorption in quartz and diamond. The emphasis in the discussion of results is on their contribution to the study of defects in solids.