Superconductivity induced by U-doping in the SmFeAsO system

TL;DR

This study demonstrates that substituting uranium into SmFeAsO induces superconductivity up to 49 K, with U doping suppressing magnetic instability and doping electrons into the system, confirmed by structural and magnetic measurements.

Contribution

First demonstration of uranium doping in SmFeAsO inducing high-temperature superconductivity and revealing its effects on structure and electronic properties.

Findings

U doping suppresses spin-density-wave instability

Superconductivity up to 49 K observed in U-doped samples

U doping introduces electrons into the system

Abstract

Through partial substitution of Sm by U in SmFeAsO, a different member of the family of iron-based superconductors was successfully synthesized. X-ray diffraction measurements show that the lattice constants along the a and c axes are both squeezed through U doping, indicating a successful substitution of U at the Sm site. The parent compound shows a strong resistivity anomaly near 150 K, associated with spin-density-wave instability.U doping suppresses this instability and leads to a transition to the superconducting state at temperatures up to 49 K. Magnetic measurements confirm the bulk superconductivity in this system. For the sample with a doping level of x = 0.2, the external magnetic field suppresses the onset temperature very slowly, indicating a rather high upper critical field. In addition, the Hall effect measurements show that U clearly dopes electrons into the material.