Magnetic band structure in the valence band of CdSb

Starting from the band structure calculations of Yamada, we have undertaken to calculate in analytic form the Landau levels, de Haas-Shubnikov oscillation periods and effective masses in the valence band of CdSb. Because of the anomalous character of the E — k relation in the x-direction, it is necessaryto use different approximation methods for low and high hole energies; between the two is a region for which calculation is very difficult. Analytic forms have been obtained in both regimes, which should facilitate the calculation of magneto-transport properties and thus the determination of band parameters.     

Optical properties and band structure of CdSb

The optical constants of CdSb were determined for photon energies up to 2 eV from reflectivity measurements and by using the Kramers-Kronig dispersion relation. The experimental set-up for the reflectivity measurements is described. Possible locations of the observed direct transitions are found by the application of the selection rules. It is shown how these results, together with some results regarding the transport properties of CdSb, can be used to obtain information about the structure of the valence and conduction bands.     

On the electron band structure of liquid metals

The electronic structure and the density of states of simple liquid metals is discussed on the basis of a nonlocal and energy-dependent pseudopotential of the Phillips-Kleinman type. As an example we treat lithium. To calculate this pseudopotential we need to know the states and the eigenvalues of the liquid metal ion cores. For these quantities we use: first, the core data of the free atom; second, of the free ion; third, the data we have determined from the measured phonon dispersion curves. The deviations between the band structures, the density of states as calculated with these pseudopotentials and those of free electrons are considerable.     

Absorption edge of CdSb

Measurements of the absorption of CdSb near the absorption edge at temperatures of 300°, 200°, 80° and 15°K were carried out. The structure of the absorption edge was interpreted by means of indirect allowed transitions.     

On the electronic band structure of zigzag-type single-walled carbon nanotubes

The electronic band structure of a zigzag-type carbon nanotube has been computed by using the tight-binding approximation method in the framework of SSH Model Hamiltonian modified by the inclusion of two Lagrange multipliers instead of one. This modification yielded an electronic band structure consistent with the experimental reports that an infinite (3,0) zigzag-type single-walled carbon nanotubes displays a metallic behaviour.     

On the study of amorphous material band structure by current injection

A theory for trap-controlled transient current injection is developed for an arbitrary distribution of traps into the gap. A model of trapping level distribution is suggested, which explains the latest data on some amorphous materials.     

Refining of CdSb and preparation of CdSb single crystals by zone melting

CdSb single crystals were prepared by zone melting in a boat both with and without a seed crystal in a stream of pure hydrogen or in a sealed and evacuated tube. The zone moved with a velocity of 1–20 cm/hour. Zone melting in an evacuated tube was used to prepare CdSb single crystals of high purity containing 10¹⁵ acceptors/cm³ at room temperature. During zone refining the stoichiometry is damaged; the front part of the ingot is enriched by cadmium and the end of the ingot by antimony; the enrichment is of an order of several percent after 10 passages of the zone. In the middle part of the ingot the stoichiometric compound remains unchanged. CdSb single crystals grow even by directional cooling of the melt of the stoichiometric compound without a seed crystal.

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CdSb CdSb

CdSb 1–20 cm/, . CdSb CdSb , 10¹⁵ cm³ . ; , . . . CdSb .

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The author died 28. 5. 1961.     

Infrared spectra of CdSb

We present new measurements of infrared reflectivity of CdSb crystals. Phonons were detected for the three crystallographic axes and fitted with the factorized oscillator model. Fourteen out of the fifteen predicted phonons were detected.     

On the specific features and transformation of the band structure of mercury-based HTSC compounds

A systematic analysis of the temperature dependences of the thermopower S(T) for different phases of the HgBa₂Ca _n?1Cu _n O_2n+2+δ family (n=1, 2, 3) at different doping levels is performed in the framework of a narrow-band phenomenological model. Quantitative estimates of the main parameters of the band responsible for conduction in the normal phase of HgBa₂Ca _n?1Cu _n O_2n+2+δ are given for optimally doped samples. The character of the variation in these parameters with an increasing number n of the copper-oxygen layers is discussed. A trend toward broadening of the conduction band with increasing n is revealed, which can be due to the increase of the density-of-states (DOS) peak near the Fermi level with an increasing number of the CuO₂ layers responsible for the formation of the conduction band. It is found that an increase in the number n leads to an increase in the fraction of localized carriers in the band owing to a more defective structure observed in the more complex phases of HgBa₂Ca _n?1Cu _n O_2n+2+δ. The variations in the band-structure parameters in going from under-to overdoped compositions in the HgBa₂Ca _n?1Cu _n O_2n+2+δ family are also discussed.     

The chemical bond in CdSb

The MO LCAO method is used to show that in CdSb there probably exist electron-deficient bonds in addition to covalent bonds. The proposed bond scheme is compared with the results, obtained up to now with CdSb.The authors thank Dr. A. Línek and Dr. K. Toman for valuable discussions and K. Trnková for performing the numerical calculations.     

The magnetic susceptibility of p-type CdSb

The paper gives the measurements of the magnetic susceptibility of p-type CdSb at 77°K on samples crystallographically oriented and cut from single crystals having an acceptor concentration of 2.3×10¹⁵cm^–3, 2.4×10¹⁶ cm^–3 and 1.5×10¹⁷ cm^–3. The anisotropy of the lattice and hole gas contribution was found and the ratio of the hole effective mass obtained from measurement of the transversal magnetoresistivity in p-type CdSb at 77°K [3] was used to determine their absolute values:m _a=0.48m ₀=m _b=0.44m ₀,m _c=0.17m ₀.     

Anisotropy of chemical bond in CdSb compound

Mooser's and Pearson's assumption as to the type of bonds in CdSb is confirmed by determining the cleavage, the anisotropy of the linear expansion and to a certain extent also the anisotropy of the amplitude of the thermal vibrations.     

The band structure of polyferrocenylene

The band structure of polyferrocenylene is studied by means of crystal orbital calculations based on a semiempirical INDO model. The width for the highest filled bands is found between 0.40 to 2.61 eV. The closely spaced basis energies of ligand π and Fe 3d states lead to a strong metal-ligand intermixing in the k-space.