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The heavy-electron compound URu2Si2 exhibits two electronic phase transitions: superconductivity at T, =1.5 K and a second transition at To--17.5 K. The specific-heat anomaly associated with the transition at To has a mean-field BCS-like form which suggests the formation of a chargeor spin-density wave that partially gaps the Fermi surface. Through electrical-resistivity measurements, we have studied the influence of pressure P up to -15.4 kbar on these transitions. For pressures less than 12 kbar, To increases linearly at a rate -130 mK/kbar, while T, decreases linearly at a rate -95 mK/kbar. The nearly equal but opposite P dependences of To and T, suggest a cornpetition for electronic density of states at the Fermi level. The resistivity, when normalized to its maximum value p(T "),scales as a function of reduced temperature T/T, "(P) from T, to well above T a"except in the immediate vicinity of To.

We have measured the thermal conductivity of superconducting films of indium-bismuth alloys in a perpendicular magnetic field. The films were condensed onto glass substrates held at 77 K, and had thicknesses ranging from 1050 to 4570 A. Values of the ratio of the BCS coherence length to the electron mean free path for these films were 9. We made measurements at temperatures T between 0.3 and 1.0 K for magnetic fields ranging from zero to above the upper. critical field H". We plotted the thermal conductivity as a function of magnetic field. The resulting curve, except for some rounding very close to H, 2, was found to be approximately linear for magnetic fields greater than 60% of H". This linear behavior is in qualitative agreement with the theory of Caroli and Cyrot for the electronic part of the thermal conductivity of a dirty superconductor near H". This theory predicts that the ratio of the slope of the thermal-conductivity curve to the slope of the magnetization curve at H" is a universal function of the reduced temperature t = T/T"where T, is the zero-field transition temperature. We infer the magnetization of our films with the help of theoretical calculations which are based on the critical-field values. The experimental values of the ratio of the slopes are 10 -30% below the theoretical values. In attempting to explain this discrepancy, we speculate that v, varies more rapidly as a function of temperature than theory predicts. The same conclusion has been drawn previously from both similar and different types of experiments.

Electron theory of the magnetic moment structure of αFe, εCo, Ni from neutron diffraction experiment AIP Conf.