J.M. Ziman

Bio: J.M. Ziman is an academic researcher from University of Cambridge. The author has contributed to research in topics: Fermi surface & Anisotropy. The author has an hindex of 1, co-authored 1 publications receiving 165 citations.

The ordinary transport properties of the noble metals

Abstract: The Fermi Surfaces in Cu, Ag and Au are now known to be greatly distorted, with thick ‘necks’ passing through the zone boundaries. In this paper we enquire whether such an electronic structure is quantitatively consistent with the observed transport coefficients. The mathematical model is quite simple; the shape of the Fermi surface is made to depend on a single parameter which can be interpreted as the pseudo-potential of the {111} atomic planes acting on an orthogonalized plane wave, giving rise to an energy gap of 5–10 ev at the zone boundaries. Various integrals over the Fermi surface can then be evaluated by elementary methods, and compared with the corresponding experimental quantities. The electronic specific heat and optical mass in the pure metals are consistent with the model. The galvanomagnetic effects are shown to depend a great deal on the anisotropy of the electron relaxation time, whose variation with energy is also probably the electron relaxation time, whose variation with energ...

Positron studies of condensed matter

Abstract: This review is concerned with the utilization of the positron-electron annihilation phenomenon in studies of the physics of condensed matter. The theory of the annihilation process is outlined, the importance of the two-photon mode of decay is established, and it is described how the observable results depend on the initial positron and electron states of the system. A brief account of the principal experimental techniques is included. Discussion of the complex nature of positron behavior in molecular substances suggests the particular value of investigations directed at the two photon pick-off mode of decay of the orthopositronium atoms that are formed in these materials. The possibility of positronium formation in ionic and metallic materials is also considered. The many important electron aspects of positron annihilation in metals are dealt with. The independent particle approach to the analysis of two photon angular distributions is discussed and illustrated. A survey of electronic structure investigations includes studies of polycrystalline and single crystal specimens. The relevance of angular correlation measurements in investigations of the Fermi surfaces of metals and alloys is discussed. More recently developed applications to the study of defected and disordered systems are dealt with. A preliminary account of the interpretation of multicomponentmore » lifetime spectra in terms of varying numbers of distinguishable positron states provides the basis for a discussion of studies of positron trapping by defects, voids. and surfaces in ionic and metallic solids, liquids and powders. (auth)« less

Low-Temperature Properties of Silver

Abstract: Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconductor material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here the authors present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability. 215 refs., 48 figs.

Electronic Properties of Liquid Metals and Alloys

Abstract: Publisher Summary During the past decade, there has been an increasing interest in the properties of noncrystalline conductors such as liquid metals, metallic vapors in the critical region, metal-ammonia solutions, and vitreous and amorphous semiconductors. The strict periodicity or long-range order of the atomic arrangement—the basic assumption in solid state theory—is lost in these materials. The noncrystalline state influences mainly the electronic transport properties. Liquid metals are best suited for the investigation of the noncrystalline state because of their well-defined atomic distribution and because of the good reproducibility of the experimental results. However, many experimental difficulties, such as those associated with the application of high temperatures and the effect of corrosion, are encountered in their study. This chapter summarizes the experimental situation of the electronic and magnetic properties of liquid normal, transition, and rare earth metals and their alloys. The experimental data are compared with the results of recent theories which give a possible understanding. But the main aim of this chapter is to make the results known to a larger community and to initiate critical remarks regarding the often very simple models that have been employed. Furthermore, it would be desirable to attain new explanations and detailed comparisons with the explanations of the same effects in the solid state. Throughout this chapter the differences and similarities between the solid and liquid state are emphasized. The section on liquid normal metals is a summary of well-established experimental data and theoretical explanations.

The Fermi surfaces of copper, silver and gold. II. Calculation of the Fermi surfaces

Abstract: Fermi surfaces, similar in shape to that proposed for copper by Pippard, have been computed which fit Shoenberg’s experimental measurements of the de Haas-van Alphen effect in copper, silver and gold. It is shown that these are reasonably consistent with other experimental results, particularly the anomalous skin measurements of Pippard and Morton, although the shapes of the surfaces are markedly different in detail from the surfaces proposed by Pippard and Morton. Consideration has been given to using the cyclotron resonance data of Kip, Langenberg & Moore to deduce electron velocities, but without success.

Thermoelectricity in Metals and Alloys

Abstract: Publisher Summary The three thermoelectric phenomena which are associated with the names Seebeck, Peltier, and Thomson were all discovered in the past century. However, only in the last 30 years or so have the thermoelectric properties of solids been investigated in detail. While the initial experiments had established the main physical behavior of thermoelectricity in many materials, thermoelectricity has recently been used as a more and more sophisticated tool for studying electron and phonon scattering in solids and even for probing the Fermi surface in metals and alloys. For many metals, a qualitative understanding of the thermoelectric properties has now emerged, taking into account the details of the Fermi surface and of the electron-phonon interaction. This chapter summarizes the present knowledge about thermoelectricity in metals and alloys, both experimentally and theoretically. Rather short accounts of thermoelectricity have been given earlier in a number of texts. An excellent survey of thermoelectricity was presented about ten years ago by MacDonald. It is this book by MacDonald that comes perhaps closest to the aim of the present chapter. Needles to say, during the past decade the field of thermoelectricity has seen progress on numerous sides. This chapter concentrates mainly on the results, both of experiment and theory.