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A comprehensive study of selected properties of amorphous (a) Cu–TE alloys (TE = Ti, Zr and Hf) has been performed. Data for average atomic volumes of a-Cu–Hf, Ti alloys combined with literature data show that ideal solution behaviour (Vegard’s law) extends over the whole glass forming range (GFR) in all a-Cu–TE alloys. This enables one to obtain an insight into some properties and probable atomic arrangements for both, a-TEs (Ristić et al., 2010) and a-Cu by extrapolation of the data for alloys. Indeed the atomic volumes and other properties studied for all a-Cu–TE alloys extrapolate to the same values for a-Cu. Depending on the property, these values are either close to those of crystalline (c) Cu, or are close to those for liquid (L) Cu. In particular, the electronic transport properties of a-Cu seem close to those of L-Cu, whereas the static properties, such as the density of states, and Young’s modulus, converge to those of c-Cu. The possible impact of these results on our understanding of a-Cu–TE alloys, including glass forming ability, is discussed. [ABSTRACT FROM AUTHOR]

Abstract: Thermopower and magnetization studies of epitaxial thin films and sintered polycrystalline ceramics of RuSr2GdCu2O8 show evidence for the occurrence of a spin-flop transition, consistent with earlier neutron diffraction data. Realignment of spins in a magnetic field enhances T c by up to 4K, presumably due to reduced magnetic pair-breaking. Specific heat and powder AC susceptibility measurements give strong evidence for bulk superconductivity. High temperature magnetization measurements indicate in-plane ferromagnetic correlations which remain to be reconciled with low-temperature neutron diffraction evidence for conventional G-type antiferromagnetism. [Copyright &y& Elsevier]

Abstract: We present an analysis of the intermolecular potential for the argon–ethane system. The potential energy surface has been calculated using coupled-cluster theory at the CCSD(T) level extrapolated to the complete basis set limit and has been used to develop a pairwise-additive analytic potential. We have identified two potential minima for each conformation, corresponding to axial and equatorial positions for the argon atom. We present calculated equilibrium geometries and selected spectroscopic constants for these clusters, predicting a reduction of 27cm−1 in the torsional barrier height of ethane on complexation at the equatorial position, with no change for complexation at the axial position. [Copyright &y& Elsevier]

Abstract: A previous frequency analysis including data from the torsional (ν 4) stack of the ground vibrational state as well as the lowest-frequency perpendicular fundamental ν 9 of CD3CD3 has been extended to include new data for the weaker but infrared-active ν 9 + ν 4 − ν 4 hot band. Analysis is complicated by the small torsional splitting due to barrier height in both the ν 9 and hot band data. The combined data set includes more than 2600 frequencies, and was fitted to within experimental accuracy using a 34-parameter model Hamiltonian. Remarkably, no resonances were observed between the upper state and the bath states, and no new intervibrational interactions were required in analyzing the hot band data. The barrier dependence of several purely vibrational terms, however, was found to be important. This represents the first reported global fit analysis including an associated hot band of a degenerate vibrational fundamental for any ethane-like molecule. [Copyright &y& Elsevier]

Abstract: A batch mode process has been developed to produce a 76Kr (h) radioactive ion beam at the Lawrence Berkeley National Laboratory 88-in. Cyclotron. First, a 6 particle μA α beam is run for 17h to produce approximately 1014 76Kr atoms via the reaction 74Se(α, 2n)76Kr. Then, the krypton is separated from the target material and injected into the AECR-U ion source. Beam intensities as high as 3×108 particles per second are observed with an integrated beam current of 6(2)×1011 particles per 24-h batch cycle. [Copyright &y& Elsevier]

The g factor of the first 2+ state of radioactive 76Kr (T1/2=14.8 h) has been measured, extending the systematics of the previously measured stable 78, 80, 82, 84, 86Kr isotopes. The measurement was performed with a radioactive 76Kr ion beam applying projectile Coulomb excitation in inverse kinematics combined with the transient magnetic field technique. The 76Kr beam was produced and accelerated in batch mode (re-cyclotron method) at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. A total of three production and acceleration cycles yielded six hours of beam on target with peak rates of 108 particles/s. About 5.6×104 particle-γ coincidence events were recorded. The g factor g(76Kr;2+1)=+0.37(11) was obtained by direct comparison to the known g(78Kr;2+1) value re-measured immediately after the 76Kr runs with the same setup and under almost identical kinematic conditions. [Copyright &y& Elsevier]

The lowest frequency parallel fundamental band ν5 of CH3CD3 near 900 cm−1 has been measured at low temperature with a resolution of 0.002 cm−1 using Fourier transform spectroscopy. The band is weak and an absorption path of 60 m was used. Large torsional splittings due to inter-vibrational coupling have been observed. Building on previous studies of the torsional levels in the ground vibrational state and in the methyl rocking state ν12, a three-band analysis including these most recent data have been completed. The combined data set of almost 2 700 frequencies was fitted to within experimental accuracy using a 45-term model Hamiltonian. The results were found to bear a striking resemblance in most respects to those of an earlier, analogous study of CH3SiH3. In addition to the interactions described in that work, however, the present study indicates an important but local coupling between the (v5=1,v6=0) and (v12=1,v6=1) states of CH3CD3. This coupling has a strong effect on the K=7 lines of the ν5 band, which have been successfully assigned and fitted here. [Copyright &y& Elsevier]

The effects of planar hole concentration, p, and in-plane disorder, Zn (y), on the DC resistivity, ρ(T), of sintered samples of Y1−xCaxBa2(Cu1−yZny)3O7−δ were investigated over a wide doping range by changing both the oxygen deficiency (δ) and Ca content (x). From the ρ(T,p) data we extracted characteristic crossover temperatures on the underdoped and overdoped sides, T* and Tm respectively, above which ρ(T) is linear. We compare our results with a number of other polycrystalline, thin film and single crystal cuprate superconductors and find similar behavior in the p-dependence of T*(p), Tm(p), and the resistivity exponent, m(p), in fits to ρ(T)=ρ0+aTm on the overdoped side. Our findings suggest that the doping level p=0.19±0.01 is special and could possibly be a quantum critical point in the sense that a transition between two different states takes place at zero temperature at this doping (pcrit). [Copyright &y& Elsevier]

In this paper we review and expand our previous report concerning the observation of de Haas–van Alphen (dHvA) oscillations in single crystals of the high temperature superconductor MgB2. The analysis of these oscillations provides an important and precise check of band-structure calculations, as well as a measure of the many body electron–phonon interactions, which enhance the quasi-particle effective masses and give rise to superconductivity. Orbits are observed on both the σ and π bands, with dHvA frequencies in good agreement with recent calculations. By comparing the measured quasi-particle effective masses with band masses calculated recently by three groups, we find that the electron–phonon coupling strength λ is a factor ∼3 larger on the 2D σ orbits than on the 3D π orbits, in accord with recent microscopic calculations. We are therefore able to verify two of the key ingredients in the two-gap model of superconductivity in this compound, namely the Fermi surface topology and the disparity in the electron–phonon coupling for the σ and π bands. [Copyright &y& Elsevier]

Abstract: The effects of planar hole content, p, on the temperature-dependent uniform (q =0) magnetic susceptibility, χ(T), of polycrystalline Y1−x Ca x Ba2Cu3O7−δ compounds with 0.0⩽ x ⩽0.20 were investigated over a wide range of oxygen deficiency (δ). Systematic variations in χ(T) were found with changing p. The characteristic pseudogap temperature scale, E g(p)/k B, was extracted from the analysis of the χ(T, p) data. We have found clear evidence that the pseudogap in the quasi-particle spectral weight appears abruptly at a planar hole content of p ∼0.19, and that it grows rapidly with decreasing p. [Copyright &y& Elsevier]