Proximity Effect - Amorphous Sn-Fe, Amorphous Bi-Fe Films

Journals published by the American Physical Society can be found at http://journals.aps.org

Specific-Heat of the Organic Metal Bis(tetrathiotetracene) Tri-Iodide from 20-K to 100-K, the Vicinity of the Metal-Nonmetal Phase-Transition

Journals published by the American Physical Society can be found at http://journals.aps.org

Correlation between the extraordinary Hall constant and electrical resistivity minima in Co-rich metallic glasses

Journals published by the American Physical Society can be found at http://journals.aps.org/The Hall effect has been studied in some Co-rich ferromagnetic metallic glasses which show resistivity (rho) minima at low temperatures. It is found that the extraordinary Hall constant (R-s) shows a corresponding minimum. The scaling relation R(s)similar torho(n) holds with nsimilar or equal to2 showing the dominance of quantum transport in these high-resistive disordered systems. The temperature dependences of magnetization and electrical resistivity are also interpreted in terms of existing theories

Eliashberg Function in an Amorphous Simple Metal Alloy Sn1-Xcux Determined by Electron-Tunneling

Journals published by the American Physical Society can be found at http://journals.aps.org

Thermal transport of the single-crystal rare-earth nickel borocarbides RNi2B2C

Journals published by the American Physical Society can be found at http://journals.aps.org/The quaternary intermetallic rare-earth nickel borocarbides RNi2B2C are a family of compounds that show magnetic behavior, superconducting behavior, and/or both. Thermal transport measurements reveal both electron and phonon scattering mechanisms, and can provide information on the interplay of these two long-range phenomena. In general the thermal conductivity kappa is dominated by electrons, and the high temperature thermal conductivity is approximately linear in temperature and anomalous. For R=Tm, Ho, and Dy the low-temperature thermal conductivity exhibits a marked loss of scattering at the antiferromagnetic ordering temperature T-N. Magnon heat conduction is suggested for R=Tm. The kappa data for R=Ho lends evidence for gapless superconductivity in this material above T-N. Unlike the case for the non-magnetic superconductors in the family, R=Y and Lu, a phonon peak in the thermal conductivity below T-c is not observed down to T=1.4 K for the magnetic superconductors. Single-crystal quality seems to have a strong effect on kappa. The electron-phonon interaction appears to weaken as one progresses from R=Lu to R=Gd. The resistivity data shows the loss of scattering at T-N for R=Dy, Tb, and Gd; and the thermoelectric power for all three of these materials exhibits an enhancement below T-N

Evidence for a Surface-Phonon Contribution to Thin-Film Superconductivity - Depression of Tc by Noble-Gas Overlayers

Journals published by the American Physical Society can be found at http://journals.aps.org

Spin glass behavior in FeAl2

Journals published by the American Physical Society can be found at http://journals.aps.org/Magnetic and transport measurements indicate FeAl2 to be an ordered intermetallic spin glass, with canonical behavior including a susceptibility cusp at T-f = 35 K and frequency-dependent susceptibility below T-f. The field-cooled and zero-held-cooled magnetization diverge below T-f, with hysteresis characteristic of a spin glass. A resistivity minimum just above T-f is explained in terms of coherent magnetic scattering. This behavior is common to spin glasses with short-range interactions among f-electron moments and indicates a similar spin configuration in these materials

Anisotropic magnetoresistance of single-crystal HoNi2B2C and the interplay of magnetic and superconducting order

Journals published by the American Physical Society can be found at http://journals.aps.org/The in-plane resistivity and magnetization measurements as a function of the magnitude and direction of the magnetic field and the temperature are reported for single-crystal samples of the HoNi2B2C magnetic superconductor. Features corresponding to several distinct magnetic phases and the coexistence of superconductivity with two of the magnetic phases are observed. Contrary to previous measurements for polycrystalline samples, reentrant superconductivity is not observed in the absence of a field for these samples. The measurements indicate an extremely rich interplay between superconductivity and different magnetic structures that can be influenced by field, temperature, and current. The results correlate quantitatively with and complement previous determinations of the magnetic phase diagram and qualitatively with determinations of the superconducting phases by measurements of the single-crystal magnetization and heat capacity. HoNi2B2C is highly anisotropic, and phase diagrams for the field along the (100) and (001) directions are presented

Transport and superconducting properties of RNi2B2C (R=Y, Lu) single crystals

Journals published by the American Physical Society can be found at http://journals.aps.org/The in-plane resistivity, in-plane absolute thermopower, and upper critical held measurements are reported for single-crystal samples of YNi2B2C and LuNi2B2C superconductors. The in-plane resistivity shows metallic behavior and varies approximately linearly with temperature near room temperature (RT) but shows nearly quadratic behavior in temperature at low temperatures. The YNi2B2C and LuNi2B2C single-crystal samples exhibit large transverse magnetoresistance (approximate to 6-8% at 45 kOe) in the ab plane. The absolute thermopower S(T) is negative from RT to the superconducting transition temperature T-c. Its magnitude at RT is a few times of the value for a typical good metal. S(T) is approximately linear in temperature between approximate to 150 K and RT. Extrapolation to T = 0 gives large intercepts (few mu V/K) for both samples suggesting the presence of a much larger ''knee'' than would be expected from electron-phonon interaction renormalization effects. The upper critical fields for H parallel and perpendicular to the c axis and the superconducting parameters derived from it do not show any anisotropy for the YNi2B2C single-crystal samples in agreement with magnetization and torque magnetometry measurements, but a small anisotropy is observed for the LuNi2B2C single crystals. The analysis shows that these are moderately strong-coupling type-II superconductors (similar to the A-15 compounds) with a value of the electron-phonon coupling parameter lambda(0) approximately equal to 1.2 for YNi2B2C and 1.0 for LuNi2B2C, the Ginzburg-Landau coherence length xi(0) approximately equal to 70 Angstrom, and H-c2(0) similar to 60-70 kOe. The temperature dependence of the upper critical field shows a positive curvature near T-c in disagreement with the Werthamer, Helfand, Hohenberg, and Maki (WHHM) theory but in agreement with a recent solution of the Gor'kov equation using a basis formed by Landau levels (Bahcall); however, the data show a severe disagreement between the observed low-temperature behavior of H-c2(T) and that predicted either by WHHM or Bahcall's expressions

Side-Jump Effect in Paramagnetic Amorphous Metals

Journals published by the American Physical Society can be found at http://journals.aps.org/A systematic study of the resistivity (rho), the Hall coefficients (R(H)), and the magnetic susceptibilities (chi) of the Zr-based paramagnetic amorphous alloys suggests a self-consistent explanation for the frequently observed positive values of R(H) that is based on. the side-jump effect. Measurements for chi, R(H), and rho of (Zr0.64Cu0.36)1-xAlx and chi for (Zr0.50Ni0.50)1-xAlx alloys are presented. The odd behavior of the Hall coefficients of these alloys and the anomalous positive Hall coefficients of paramagnetic Zr-based amorphous alloys can be accounted for in terms of the enhanced spin-orbit interaction, which produces the side-jump effect