Doping dependent evolution of magnetism and superconductivity in Eu1-xKxFe2As2 (x = 0-1) and temperature dependence of lower critical field Hc1

Abstract

We have synthesized the polycrystalline samples of Eu1-xKxFe2As2 (x = 0-1) and carried out systematic characterization using x-ray diffraction, ac & dc magnetic susceptibility, and electrical resistivity measurements. We have seen a clear signature of the coexistence of superconducting transition (Tc = 5.5 K) with SDW ordering in our under doped sample viz. x = 0.15. The spin density wave transition observed in EuFe2As2 get completely suppressed at x = 0.3 and superconductivity arises below 20 K. Superconducting transition temperature Tc increases with increase in K content and a maximum Tc = 33 K is reached for x = 0.5, beyond which it decreases again. The doping dependent T(x) phase diagram is extracted from the magnetic and electrical transport data. It is found that magnetic ordering of Eu-moments coexists with superconductivity up to x = 0.6. The isothermal magnetization data taken at 2 K for the doped samples suggest 2+ valence states of Eu ions. We also present the temperature dependence of the lower critical field Hc1 of superconducting polycrystalline samples. The value of Hc1(0) obtained for x = 0.3, 0.5, and 0.7 after taking the demagnetization factor into account is 248, 385, and 250 Oe, respectively. The London penetration depth λ(T) calculated from the lower critical field does not show exponential behaviour at low temperature, as would be expected for a fully gapped clean s-wave superconductor. In contrast, it shows a T2 power-law feature down to T = 0.4 Tc, as observed in Ba1-xKxFe2As2 and BaFe2-xCoxAs2.

17 pages, 10 figures

References in corpus (19)

• Fermi-liquid instabilities at magnetic quantum phase transitions
• The Puzzle of High Temperature Superconductivity in Layered Iron Pnictides and Chalcogenides
• Magnetism in Fe-based superconductors
• Superconductivity induced by phosphorus doping and its coexistence with ferromagnetism in EuFe${}_2$(As${}_{0.7}$P${}_{0.3}$)${}_2$
• Electronic phase separation in the slightly underdoped iron pnictide superconductor Ba(1-x)K(x)Fe(2)As(2)
• Unconventional pairing in the iron arsenide superconductors
• Possible re-entrant superconductivity in EuFe2As2 under pressure
• Electrical Resistivity and Specific Heat of EuFe2As2 Single Crystals: Magnetic homologue of SrFe2As2
• Microwave Surface-Impedance Measurements of the Magnetic Penetration Depth in Single Crystal Ba1-xKxFe2As2 Superconductors: Evidence for a Disorder-Dependent Superfluid Density
• Unconventional London penetration depth in Ba(Fe0.93Co0.07)2As2 single crystals
• Superconductivity coexisting with phase-separated static magnetic order in (Ba,K)Fe${}_2$As${}_2$, (Sr,Na)Fe${}_2$As${}_2$ and CaFe${}_2$As${}_2$
• Coexistence of magnetic fluctuations and superconductivity in the pnictide high temperature superconductor SmFeAsO${}_{1-x}$F${}_x$ measured by muon spin rotation
• Evidence for Two Gaps and Breakdown of the Uemura Plot in Ba${}_{0.6}$K${}_{0.4}$Fe${}_2$As${}_2$ Single Crystals
• 75As NMR Study of Hole-Doped Superconductor Ba1-xKxFe2As2 (Tc = 38K)
• London penetration depth and strong pair-breaking in iron-based superconductors
• Evidence of quantum criticality in the phase diagram of K${}_x$Sr${}_{1-x}$Fe${}_2$As${}_2$ from measurements of transport and thermoelectricity
• Interplay between superconductivity and magnetism in K-doped EuFe2As2
• The superconductor KxSr(1-x)Fe2As2: Normal state and superconducting properties
• Lower Critical Field, Anisotropy, and Two-Gap Features of LiFeAs

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