Superconducting and magnetic properties of (Th1−xNdx)Ru2 and (Th1−xLax)Ru2 intermetallic compounds

Abstract

The superconducting properties of (Th1−xLax)Ru2 and the superconducting and magnetic properties of (Th1−xNdx)Ru2 are investigated by ac-susceptibility and dc-magnetization measurements as a function of temperature and applied pressure. Both systems exhibit an unusual increase of the superconducting transition temperature Tc for 0≤x≤0.33. For the first time we are able to separate the magnetic contribution in (Th1−xNdx)Ru2 by subtracting the Tc values of both systems. The difference of the Tc values at the respective concentrations shows an Abrikosov-Gor’kov (AG) type of behavior which we attribute to the weak interaction of the Nd ions with the conducting electrons. The anomalous Tc behavior is also reflected in the concentration dependence of the upper critical field Hc2(0). In contrast to Tc and Hc2(0), the calculated electron density of states at the Fermi surface decreases with increasing x. With the application of hydrostatic pressure (pmax=1.2 GPa) the Tc values in (Th1−xNdx)Ru2 show a weak pressure dependence. The reduction of Tc with pressure varies linearly with x for 0≤x≤0.20 in accordance with the AG theory. The (Th1−xLax)Ru2 compounds show no pressure dependence within the experimental accuracy (5 mK) for 0≤x≤0.3.

Source-reported materials — not catalogue approval

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