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The crystallographic and magnetic properties of CaRu 1−x Mn x O 3 ͑0 Յ x Յ 1.0͒ were investigated in detail by x-ray powder diffraction, magnetization, and magnetic Compton scattering measurements. The lattice parameters show considerable deviation from Vegard's law. Ferromagnetism appears at a relatively large Mn concentration ͑x Ն 0.2͒, and the magnetization and the Curie temperature have a maximum at a Mn content near x = 0.7. The magnetic Compton scattering measurement revealed that Mn makes a dominant contribution to the magnetization and the Mn moment is antiparallel to the Ru moment, which is induced by Mn doping. The anomalous change in the unit cell volume and the occurrence of ferromagnetism were discussed on the basis of the mixed-valence model of Mn 3+ , Mn 4+ , Ru 4+ , and Ru 5+ ions. The Mn-composition dependence of the spontaneous magnetization was explained semiquantitatively assuming ͑1͒ ferromagnetic coupling between Mn 3+ and Mn 4+ ions, ͑2͒ antiferromagnetic coupling between Ru 5+ and Mn ions, and ͑3͒ the theoretical spin moments of Mn 3+ , Mn 4+ , and Ru 5+ . The ferromagnetic interaction between Mn 3+ and Mn 4+ ions seems to make a dominant contribution to the Curie temperature. The CaRu 1−x Mn x O 3 system is considered to be a ferrimagnet induced through competition between the ferromagnetic interaction between Mn ions and the antiferromagnetic interaction between Ru 5+ and Mn ions.

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We have investigated the upper critical fields of Y1-xErxNi2B2C and Y1-xErxPd5B3C0.4 (0 less than or equal to x less than or equal to 1) systems by the scaling analysis of the thermal fluctuation conductivity, The experiments were done over wide magnetic field range. We are going to test the thermal fluctuation theory in the borocarbide superconducting systems. According to the scaling analysis, the thermal fluctuation conductivity should be scaled as sigma (f) = (T-2/H)(1/3) F[AT-T-c(H)/(TH)(2/3)]. Because the scaling function is field independent, all scaling curves obtained under various applied fields should converge to a universal curve if the function of T,(H) is properly chosen. We therefore obtain H-c2(T) determined by optimizing the scaling fit, The superconducting coherence length and Ginzburg-Landau parameter kappa in those superconductors are also estimated. We categorize the Y1-xErxNi2B2C and Y1-xErxPd5B3C0.4 systems as strong type-II superconductors