Competition of local-moment ferromagnetism and superconductivity in Co-substituted EuFe2As2

Abstract

In contrast to SrFe2As2, where only the iron possesses a magnetic moment, in EuFe2As2 an additional large, local magnetic moment is carried by Eu2+. Like SrFe2As2, EuFe2As2 exhibits a spin-density wave transition at high temperatures, but in addition the magnetic moments of the Eu2+ order at around 20 K. The interplay of pressure-induced superconductivity and the Eu2+ order leads to a behavior which is reminiscent of re-entrant superconductivity as it was observed, for example, in the ternary Chevrel phases or in the rare-earth nickel borocarbides. Here, we study the delicate interplay of the ordering of the Eu2+ moments and superconductivity in EuFe1.9Co0.1As2, where application of external pressure makes it possible to sensitively tune the ratio of the magnetic (T_C) and the superconducting (T_{c,onset}) critical temperatures. We find that superconductivity disappears once T_C > T_{c,onset}.

4 pages, 4 figures, submitted to the proceedings of SCES2010

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Cited by in corpus (5)

• RbEu(Fe${}_{1-x}$Ni${}_x$)${}_4$As${}_4$: From a ferromagnetic superconductor to a superconducting ferromagnet
• Effect of Ni-doping on magnetism and superconductivity in Eu0.5K0.5Fe2As2
• Strongly anisotropic antiferromagnetic coupling in EuFe2As2 revealed by stress detwinning
• Re-entrance of resistivity due to the interplay of superconductivity and magnetism in $\ce{Eu_{0.73}Ca_{0.27}(Fe_{0.87}Co_{0.13})2As2}$
• Effect of Co doping and hydrostatic pressure on SrFe2As2