Magnetic phase transformations and superconductivity in Dy0.8Y0.2Rh4B4

The results of experimental studies of the magnetic and the superconducting properties of the compound Dy0.8Y0.2Rh4B4 with tetragonal body-centered crystal structure of the perovskite type (LuRu4B4) are presented. It is shown that the compound undergoes a paramagnet-ferrimagnet phase transition at the Curie temperature TC≈30.5K and its magnetic compensation temperature Tcomp≈17K. According to resistance measurements, the compound becomes a ferrimagnetic superconductor at Tconset≈5.9K which undergoes a ferrimagnet-antiferromagnet phase transition at TN≈2.7K while still remaining a superconductor. The specific heat exhibits a sharp maximum at this temperature. Point-contact Andreev reflection spectroscopy is used to measure the temperature and field dependences of the order parameter Δ(T,H) and the temperature dependence of the upper critical field Hc2(T). The dependences obtained differ radically from those generally accepted for conventional superconductors. The results obtained are discussed in connectio...

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