Ellipsometric measurements of the dielectric constant of undoped Ge were performed between 1.25 and 5.6 eV in the temperature range of 100 to 850 K. The dependence of the ${E}_{1}$, ${E}_{1}+{\ensuremath{\Delta}}_{1}$, ${E}_{0}^{\ensuremath{'}}$, and ${E}_{2}$ critical energies on temperature was obtained. It can be represented either with Varshni's empirical formula or with an expression proportional to the Bose-Einstein statistical factor of an average phonon. Broadening parameters, amplitudes, and phase angles for the corresponding critical points were also obtained. A decrease of the excitonic interaction with increasing temperature was found. The results are discussed in the light of recent calculations of the effect of temperature on the band structure of Ge containing Debye-Waller and self-energy contributions.

Temperature dependence of the dielectric function of germanium

The physical properties of many of the rare-earth intermetallic compounds have been collected together. They are discussed in terms of the role that the magnetic exchange and crystal field interactions play in determining these properties. It is pointed out that in this vast number of materials there is an ideal chance of establishing which of several second-order terms are effective in determining structural stability.

Intermetallic rare-earth compounds.

A review is given of the physical properties, composition and crystal structure of intermetallic compounds formed between rare-earth elements and non-magnetic metals, with emphasis on the magnetic properties. Included are the properties of compounds in which the non-rare-earth component is a 4d or 5d transition element. Special consideration is given to the properties of pseudo-binary compounds. Results of magnetisation measurements, neutron diffraction and neutron scattering are discussed together with results derived from NMR, ESR and Mossbauer effect spectroscopy. An evaluation is given of the relevance of the experimental results with respect to different types of exchange interactions in this class of intermetallics. Special consideration is also given to the influence of crystal field effects on the magnetic properties and, furthermore, to the occurrence of intermediate valences in several of the compounds of Ce, Sm, Eu and Yb.

https://iopscience.iop.org/article/10.1088/0034-4885/42/8/003/pdf

Intermetallic compounds of rare earths and non-magnetic metals

Numerical modeling of superconductors is widely recognized as a powerful tool for interpreting experimental results, understanding physical mechanisms, and predicting the performance of high-temperature-superconductor (HTS) tapes, wires, and devices. This is particularly true for ac loss calculation since a sufficiently low ac loss value is imperative to make these materials attractive for commercialization. In recent years, a large variety of numerical models, which are based on different techniques and implementations, has been proposed by researchers around the world, with the purpose of being able to estimate ac losses in HTSs quickly and accurately. This paper presents a literature review of the methods for computing ac losses in HTS tapes, wires, and devices. Technical superconductors have a relatively complex geometry (filaments, which might be twisted or transposed, or layers) and consist of different materials. As a result, different loss contributions exist. In this paper, we describe the ways of computing such loss contributions, which include hysteresis losses, eddy-current losses, coupling losses, and losses in ferromagnetic materials. We also provide an estimation of the losses occurring in a variety of power applications.

Computation of Losses in HTS Under the Action of Varying Magnetic Fields and Currents

A general treatment of losses in multifilamentary superconductors

Effective resistance of current-carrying superconducting wire in oscillating magnetic fields 1: Single core composite conductor

Alternating field losses in superconducting wires carrying dc transport currents: Part 1 single core conductors

Rare earth intermetallic compounds in Gd(Ag, Cd, In) and Gd(Cu, Ag, Au) systems have been studied. Most of these compounds have the CsCl type of crystal structure. Magnetization measurements have been made on these compounds to determine the type of the magnetic order and its relationship to the number of conduction electrons. GdAg, GdAg 0.9 In 0.1 , GdAg 0.2 In 0.8 , GdAg 0.1 In 0.9 , and GdIn in the Gd(Ag, In) system and GdCu, GdAg, GdAg 0.7 Au 0.3 , and GdAg 0.5 Au 0.5 in the Gd(Cu, Ag, Au) system are antiferromagnetic at low temperatures. On the contrary, GdCd, GdAg 0.8 In 0.2 , GdAg 0.7 In 0.3 , GdAg 0.5 In 0.5 , and GdAg 0.3 In 0.7 are ferromagnetic at low temperatures. GdCd has a very high Curie temperature of 262°K. In the Gd(Cu, Ag, Au) system, the Neel temperature increases with the increase in the lattice constant. The remarkable difference in magnetic behavior between the Gd(Ag, Cd, In) system and the Gd(Cu, Ag, Au) system is considered to be associated with the fact that the number of conduct...

Magnetic Properties of Rare Earth Intermetallic Compounds in Gd(Ag, Cd, In) and Gd(Cu, Ag, Au) Systems

Magnetic properties of disilicides of Gd, Tb, Dy, Ho, and Er have been investigated at temperatures ranging from 4.2°K to room temperature. All the disilicides except ErSi 2 have the orthorhombic ThSi 2 type of crystal structure and are shown to be antiferromagnetic. The Neel temperatures of GdSi 2 , TbSi 2 , DySi 2 and HoSi 2 are 27°K, 17°K, 17°K, and 18°K, respectively. The compound ErSi 2 has the hexagonal AlB 2 type of crystal structure and is paramagnetic at above 4.2°K. The paramagnetic Curie temperature of these compounds decreases with the number of f electrons of the rare earth ion.

Ko Yasukochi

Papers

Effective resistance of current-carrying superconducting wire in oscillating magnetic fields 1: Single core composite conductor

Alternating field losses in superconducting wires carrying dc transport currents: Part 1 single core conductors

Magnetic Properties of Rare Earth Intermetallic Compounds in Gd(Ag, Cd, In) and Gd(Cu, Ag, Au) Systems

Antiferromagnetism of Disilicides of Heavy Rare Earth Metals

Transient field losses in multifilamentary composite conductors carrying dc transport currents