Archive | 2019
Features of Excess Conductivity Behavior in a Magnetic Superconductor Dy$_{0.6}$Y$_{0.4}$Rh$_{3.85}$Ru$_{0.15}$B$_4$
Abstract
The temperature dependencies of the excess conductivity σ0(T) and possible pseudogap (PG), Δ*(T), in a Dy0.6Y0.4Rh3.85Ru0.15B4 polycrystal were studied for the first time. It was shown that σ0(T) near Tc is well described by the Aslamazov–Larkin (AL) fluctuation theory, demonstrating a 3D–2D crossover with increasing temperature. Using the crossover temperature T0, the coherence length along the c axis, ξc(0), was determined. Above the level of T2D > T0, an unusual dependence σ0(T) was found, which is not described by the fluctuation theories in the range from T0 to TFM, at which a ferromagnetic transition occurs. The range in which superconducting fluctuations exist is apparently quite narrow and amounts to ΔTfl≈ 2.8 K. The resulting temperature dependence of the PG parameter Δ*(T) has the form typical of magnetic superconductors with features at Tmax ≈ 154 K and the temperature of a possible structural transition at Ts∼ 95 K. Below Ts, dependence Δ*(T) has a shape typical for PG in cuprates, which suggests that the PG state can be realized in Dy0.6Y0.4Rh3.85Ru0.15B4 in this temperature range. Comparison of Δ*(T) with the Peters–Bauer theory made it possible to determine the density of local pairs near Tc, 〈n↑n↓〉(TG)≈ 0.35, which is 1.17 times greater than in optimally doped YBa2Cu3O7–δ single crystals. Published under license by AIP Publishing. https://doi.org/10.1063/10.0000125