14 research outputs found
Intrinsic Josephson Effects in the Magnetic Superconductor RuSr2GdCu2O8
We have measured interlayer current transport in small sized RuSr2GdCu2O8
single crystals. We find a clear intrinsic Josephson effect showing that the
material acts as a natural
superconductor-insulator-ferromagnet-insulator-superconductor superlattice. So
far, we detected no unconventional behavior due to the magnetism of the RuO2
layers.Comment: 4 pages, 5 figures, to appear in Phys. Rev. Let
The characteristics of the superconducting and magnetic phases in the polycrystalline samples of ruthenocuprates of nominal compositions RuSr2GdCu2O8, Ru0.98Sr2GdCu2O8 and Ru0.5Sr2GdCu2.5O8-d
The temperature dependencies of the resistivity for the superconducting
ruthenocuprates of nominal compositions RuSr2GdCu2O8, Ru0.98Sr2GdCu2O8 and
Ru0.5Sr2GdCu2.5O8-d were examined for the magnetic field dependent
characteristics of the superconducting transitions. The effect of the
insignificant diminishing of the Ru/Cu ratio in parent RuSr2GdCu2O8 was
confirmed as relevant for the stabilisation of the superconducting phase. Noted
differences in the compared characteristics are interpreted for possible
inhomogeneous nucleation of the superconducting phase in the parent
ruthenocuprate. The phase anisotropy in RuSr2GdCu2O8 and Ru0.98Sr2GdCu2O8 , in
presence of the compounds Ru magnetism, appears to be a cause of a significant
softening of the Hc2(T) phase line. An anomalous lowering of the
magneto-resistivity was observed in the approx. 10 K range above the onset of
the superconducting transition, which may suggest the presence of enhanced
superconducting fluctuations in the samples. The positive magnetic field shift
of the temperatures, which limit the magneto-resistivity and the specific heat
signatures of the magnetic ordered state of the Ru sub-lattice, suggests
probing the influence of the ferromagnetic Ru interactions in an effective
metallic-like conduction channel present in the samples. Superconducting
characteristics of the Ru0.5Sr2GdCu2.5O8-d reveal a significant contribution of
the Gd paramagnetic signal at low temperatures, interpreted for the presence of
a significant anisotropy of the superconducting phase. It is concluded that the
Ru-Cu substituted phases of ruthenocuprates may present an opportunity to
investigate the effectively anisotropic superconducting phase despite its
comparatively high Tc in the compounds related to the 123-type cuprate
superconductor.Comment: 12 pages, 9 figures, accepted for publicatio