Anisotropy of electric resistance and upper critical field in magnetic superconductor Dy0.6Y0.4Rh3.85Ru0.15B4

•Anisotropy of the electric resistance and critical magnetic field was discovered.•Parameters of the spin-paramagnetic and spin-orbital interactions were determined.•Anisotropy is due to rearrangement of magnetic structure induced by magnetic field.

We have measured temperature dependencies of the electric resistance R and upper critical magnetic field Hc2 of a magnetic superconductor Dy0.6Y0.4Rh3.85Ru0.15B4. The measurements were made for different angles φ of the magnetic field inclination to the direction of measuring current and revealed strong anisotropy of the behavior of R(T) and the values of Hc2(T). By using the Werthamer–Gelfand–Hohenberg theory, we determined the Maki parameter α   and the parameter of the spin-orbital interaction. For φ=0∘φ=0∘ and 90° both parameters are close to zero, thus the magnitude of Hc2(0) ≈ 38 kOe is basically limited by the orbital effect. At φ=45∘,φ=45∘, a large value of α=4.2α=4.2 indicates dominating role of the spin-paramagnetic effect in the suppression of Hc2(0) down to 8.8 kOe. We suggest that such behavior of R(T) and Hc2(T) is caused by internal magnetism of the Dy atoms which may strongly depend on the magnetic field orientation.