Effect of 3d Transition Metal Doping on the Superconductivity in Quaternary Fluoroarsenide CaFeAsF

Abstract

We examined doping effect of 3d transition metal elements (TM: Cr, Mn, Co, Ni, and Cu) at the Fe site of a quaternary fluoroarsenide CaFeAsF, an analogue of 1111-type parent compound LaFeAsO. The anomaly at ~120 K observed in resistivity (rho) vs. temperature (T) plot for the parent compound is suppressed by the doping of each TM element. Furthermore, Co- and Ni-doping (CaFe1-xTMxAsF, TM = Co, Ni) induces superconductivity with a transition temperature maximized at the nominal x = 0.10 for Co (22 K) and at x = 0.05 for Ni (12 K). These optimal doping levels may be understood by considering that Ni2+(3d8) adds double electrons to the FeAs layers compared with Co2+ (3d7). Increased x for Co or Ni breaks the superconductivity while metallic nature drho/dT > 0 is still kept. These observations indicate that Co and Ni work as electron donors. In contrast, neither of Cr, Mn nor Cu-doping induce superconductivity, yielding drho/dT < 0 in the below the rho-T anomaly temperature, indicating that these transition metal ions act as scattering centers. The two different behavior of TM replacing the Fe site is discussed in relation to the changes in the lattice constants with the doping.

15 pages, 7 figures

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Cited by in corpus (11)

• Iron based high transition temperature superconductors
• Electronic Structure of Fe-Based Superconductors
• Hydrogen in layered iron arsenide: indirect electron doping to induce superconductivity
• High-T_c superconductivity induced by doping rare earth elements into CaFeAsF
• Narrow superconducting window in Ni-doped LaFeAsO
• Itinerant antiferromagnetism in BaCr${}_2$As${}_2$
• Superconducting Properties of the $s^{\pm }$-wave state: Fe-based superconductors
• Electronic structure of BaCu${}_2$As${}_2$ and SrCu${}_2$As${}_2$: sp-band metals
• Upper critical field, critical current density and thermally activated flux flow in CaFFe0.9Co0.1As superconductor
• The calcium doping effects on the structural and electrical properties of NdFeAsO0.8F0.2
• Superconductivity above 30 K due to the introduction of oxygen in CaFeAsF