P. A. Stampe

Field and temperature dependent transport and magnetic properties of superconducting YNi2B2C

Abstract We present measurements of the AC susceptibility (at various frequencies) and the field and temperature dependence of both the magnetisation and resistivity of YNi 2 B 2 C. These data, supplemented by X-ray measurements, were collected primarily on samples produced by a chill-casting technique. Following annealing these samples display a slightly depressed T c , but considerably enhanced M IRR (and hence j c ), H c , and, to a lesser extent, H c2 . Preliminary data on unannealed specimens indicate that this enhancement accompanies the annealing stage, thus suggesting a possibly subtle role played by the defect structure.

The longitudinal and transverse magnetoresistivities and the AC susceptibility of Fe10Pt90

A summary of detailed measurements of field and temperature dependent magnetic and transport properties in F10Pt90 is presented, with particular emphasis on attempting to evaluate the influence of spin-orbit coupling. Analysis of the field dependent AC susceptibility near the Curie temperature Tc approximately=170 K enables effective exponent values to be estimated, although the presence of magnetic anisotropy arising from spin-orbit coupling prevents asymptotic exponent values from being found. The anisotropy of the magnetoresistance in this system also originates from spin-orbit coupling, and this behaviour is discussed in terms of both itinerant and localized models. A number of estimates for Tc are deduced from these different measurements and compared.

The spontaneous resistive anisotropy as a measure of exchange bond disorder

We present new measurements of the low-field resistive anisotropy (LFRA) in amorphous Fe91Zr9, with and without hydrogen loading, together with a summary of similar data previously acquired for Fe90Zr10. The temperature dependence of these data below the ferromagnetic ordering temperature Tc is compared with that predicted for the quadrupolar term ((Sz2)-S(S+1)/3) by localized models incorporating exchange bond disorder, and the magnitude of this dependence is shown to scale with bond disorder.

Superconducting properties of Fe‐doped YNi2B2C

The effects of Fe substitution for Ni in the intermetallicsuperconductor YNi2B2C are reported. Samples of nominal composition Y(Ni1−x Fe x )2B2C with x=0.01, 0.02, 0.05, and 0.1 have been prepared and subsequently characterized by x‐ray diffraction, acsusceptibility, and resistivity/magnetoresistance measurements. A summary of these data is presented, and these are compared and contrasted with both the behavior previously reported for and the conclusions drawn from Fe and Co doping in this system.

Effects of exchange bond disorder on transport measurements

Measurements of the low field resistive anisotropy (LFRA) in amorphous Fe91Zr9 with and without hydrogen loading are presented. The temperature dependence of these data is compared with model calculations of the quadrupolar term [〈〈S2Z〉T〉J−S(S+1)/3], from which it is concluded that the model calculations reproduce both the temperature and the exchange bond dependence of this transport coefficient.Measurements of the low field resistive anisotropy (LFRA) in amorphous Fe91Zr9 with and without hydrogen loading are presented. The temperature dependence of these data is compared with model calculations of the quadrupolar term [〈〈S2Z〉T〉J−S(S+1)/3], from which it is concluded that the model calculations reproduce both the temperature and the exchange bond dependence of this transport coefficient.