Anisotropy of electric resistance and upper critical field in magnetic superconductor Dy$_{0.6}$Y$_{0.4}$Rh$_{3.85}$Ru$_{0.15}$B$_4$

TL;DR

This study investigates the anisotropic behavior of electric resistance and upper critical magnetic field in the magnetic superconductor Dy$_{0.6}$Y$_{0.4}$Rh$_{3.85}$Ru$_{0.15}$B$_4$, revealing orientation-dependent effects linked to internal magnetism.

Contribution

The paper provides the first detailed analysis of anisotropy in $R(T)$ and $H_{c2}(T)$ in this specific magnetic superconductor, including the determination of Maki and spin-orbit parameters.

Findings

Strong anisotropy in $R(T)$ and $H_{c2}(T)$ behavior.

Spin-paramagnetic effects dominate at 45° orientation.

Orbital effects limit $H_{c2}(0)$ at 0° and 90° orientations.

Abstract

We have measured temperature dependencies of the electric resistance $R$ and upper critical magnetic field $H_{c2}$ of a magnetic superconductor Dy$_{0.6}$Y$_{0.4}$Rh$_{3.85}$Ru$_{0.15}$B$_4$. The measurements were made for different angles $\varphi$ of magnetic field inclination to the direction of measuring current and revealed strong anisotropy of the behavior of $R(T)$ and the values of $H_{c2}(T)$. By using the Werthamer-Gelfand-Hohenberg theory, we determined the Maki parameter $\alpha$ and the parameter of the spin-orbital interaction. For $\varphi = 0^\circ$ and $90^\circ$ both parameters are close to zero, thus the magnitude of $H_{c2}(0) \approx 38$ kOe is basically limited by the orbital effect. At $\varphi = 45^\circ$, a large value of the parameter $\alpha = 4.2$ indicates dominating role of the spin-paramagnetic effect in the suppression of $H_{c2}(0)$ down to $8.8$ kOe. We suggest that such behavior of $R(T)$ and $H_{c2}(T)$ is caused by internal magnetism of the Dy atoms which may strongly depend on the magnetic field orientation.