Superconducting and normal state properties in partially Mn substitution in FeSe superconductors

Yung-Yuan Hsu^1*, Muhammad Raheel¹

¹Department of Physics, National Taiwan Normal University, Taipei, Taiwan

* Presenter:Yung-Yuan Hsu, email:yungyuan.hsu@gamil.com

FeSe is well known as a topological superconductor whose exotic properties accompanied with its low carrier density attracts much interests in researchers. However, lacking of chemical substitution options in this system seriously limits the tunability of physical parameters for investigation, such as the carrier densities. In this report, up to 5% of Mn was substituted into FeSe superconductors. The superconducting transition Tc increases with Mn substitution and reaches its maximum of T_c ~ 11.5 K for 4% Mn substitution. The zero-temperature lower critical field H_c1(0) decreases with the substitution indicating an increase of superconducting penetration depth and possibly lowering of superconducting carrier density, which suggests the carrier density do change with doping Mn content. The systematic evolution of anisotropic superconducting penetration depth and normal state properties as a function of substitution content will be presented and discussed in detail.

Keywords: FeSe, topological superconductor, penetration depth, BEC-BCS crossover, low carrier density superconductor