We have carried out high-field resistivity measurements up to 27 T in EuFe2As2 at P=2.5 GPa, a virtually optimal pressure for the P-induced superconductivity, where Tc=30 K. The B c2-Tc phase diagram has been constructed in a wide temperature range with a minimum temperature of 1.6 K (≈0.05 × T c), for both B ab (Bc2ab) and B c (Bc2c). The upper critical fields Bc2ab(0) and Bc2c(0), determined by the onset of resistive transitions, are 25 and 22 T, respectively, which are significantly smaller than those of other Fe-based superconductors with similar values of Tc. The small B c2(0) values and the Bc2(T) curves with positive curvature around 20 K can be explained by a multiple pair-breaking model that includes the exchange field due to the magnetic Eu2+ moments. The anisotropy parameter, Γ=Bc2ab/Bc2c, in EuFe2As2 at low temperatures is comparable to that of other "122" Fe-based systems.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2011 Mar 8|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics