[en] We have studied the effect of the dipolar magnetic coupling (also known as Neel coupling or 'orange-peel' coupling) in tunneling magnetoresistive (TMR) elements. With an in situ scanning tunneling microscope we directly accessed the roughness of the films and found a close correspondence between the values for the coupling fields determined by the magneto-optical Kerr effect and the ones computed on the basis of the measured morphology parameters. We confirm an increase of the dipole coupling between the magnetic layers with decreasing barrier thickness as predicted by the model. Deviations from the theoretical predictions are observed for the case of thinner soft magnetic layers, which can be explained by reduced magnetization in very thin films. We demonstrate the importance of dipolar coupling for understanding the magnetic behavior of TMR elements by comparing TMR curves for optimized and nonoptimized structures. [copyright] 2001 American Institute of Physics

[en] We present experimental results on magnetotransport in (Y_xGd_1-x)Co₂ alloys, where the localized Gd-moments are coupled antiferromagnetically to the itinerant Co 3d electrons. The alloys are paramagnetic for x>0.85. The transport properties of the paramagnetic alloys show Kondo like anomalies. On approaching to the magnetic phase boundary from the paramagnetic region the resistivity reveals non-Fermi liquid (NFL) behaviour, indicating a presence of apparently gap-less magnetic excitations

No abstract available

[en] The thermal behaviour of Zr-based bulk metallic glasses has been investigated in situ through the glass transition by means of differential scanning calorimetry, high temperature X-ray synchrotron diffraction, electrical resistivity, and dilatometry. The temperature dependence of the X-ray structure factor can be well described by the Debye theory. The Debye temperature of the glassy and the supercooled liquid state of Zr₅₂Ti₅Cu₁₈Ni₁₅Al₁₀ is θ=412 and θ=162 K, respectively. The temperature coefficient of the electrical resistivity and the thermal expansion coefficient change also at the calorimetric glass transition temperature. The results point to a significant changes in the dynamics of molecular motion at T_g

[en] The thermal conductivity is measured in the temperature range 2 to 70 K in three single-crystal molybdenum samples having residual resistivity ratios of 68000, 35000, and 18000. In the temperature range 2 to 18 K the measured values of the thermal conductivity may be described by the equation W = A/T + BT² + CT. Equal values are found for the coefficients B and C for all three crystals (B = 1.7 x 10^-5 cm/KW, C =1.2 x 10^-4 cm/W), whereas the values for the coefficient A are related to the residual resistivity rho₀ according to the Wiedemann-Franz law (A = rho₀/L₀, L₀ Lorenz number). In the temperature range 18 < T < thetasub(D)/10 (thetasub(D) = 430 K, Debye temperature) the thermal resistivity increases more rapidly with temperature than T². (author)

[en] The aging behaviour of CrSi(W)-O films with film composition Cr₄₂Si₅₆W₂-O has been investigated as a function of the annealing conditions, aging time, storage temperature, film thickness, additional current flow, moist atmosphere and protective layer. Internal processes of the Cr-Si-based resistive film are concluded to play a subordinate role. Rather, the stability is determined by the quality of the surface sheet formed as an oxidized layer or deposited as an additional protective film. A stability ΔR/R ≅ 0.01% for 10000 h at 120degC has been reached

[en] The thermoelectric power and the electrical resistivity have been measured for a MgB₂ sample, textured by hot deformation, in the range from 100 K up to 800 K. Above 200 K, the electrical resistivity exhibits a slight negative deviation from the linear behaviour with temperature. The thermopower rises from 2.1 μV/K at 100 K to a maximum value of 6.9 μV/K at 400 K and then decreases to 5.0 μV/K at 800 K. While the resistivity can be described by a one-band Grueneisen formula, no simple explanation exists for the thermopower

[en] The thermal conductivity of V₃Si single crystals is measured within the temperature range from 0.1 to 300 K. In the temperature range above 100 K the thermal conductivity increases with increasing temperature. This behaviour is related to the deviation from linearity of the electrical resistivity at high temperatures common to A15 superconductors. At the temperature of the lattice transformation a change of both the electron-phonon scattering coefficient and the electron-defect scattering coefficient is found. In the superconducting state, the electron conductivity steeples decreases with decreasing temperature. From a fit of the measuring points to theoretical estimations the energy gap can be determined. At the lowest investigated temperatures the lattice thermal conductivity is dominating. The different scattering mechanisms determining the temperature dependence of lattice thermal conductivity are discussed. (author)

No abstract available

[en] We report thermal conductivity measurements on a single-crystal niobium specimen of resistivity ratio 33,00 over the temperature range 0.05--23K in the superconducting state and above 9.1K in the normal state. The axis of the niobium rod was [110] oriented. The surface roughness was varied by sand-blasting of the sample. The values of the thermal conductivity in the range from the lowest temperatures up to the maximal value covered a range of six orders of magnitude (lambda2 x 10^-5 Wcm^-1 K^-1 at 50mK to lambda=22 Wcm^-1 K^-1 at in accord, whereas below 2K the influence of the sample surface is discernible. The various conduction and scattering mechanisms are discussed