Weak anisotropy of the superconducting upper critical field inFe1.11Te0.6Se0.4single crystals

Abstract

We have determined the resistive upper critical field H c2 for single crystals of the superconductor Fe 1.11 Te 0.6 Se 0.4 using pulsed magnetic fields of up to 60 T. A rather high zero-temperature upper critical field of 0 H c2 ͑0͒Ϸ47 T is obtained in spite of the relatively low superconducting transition temperature ͑T c Ϸ 14 K͒. Moreover, H c2 follows an unusual temperature dependence, becoming almost independent of the magnetic field orientation as the temperature T → 0. We suggest that the isotropic superconductivity in Fe 1.11 Te 0.6 Se 0.4 is a consequence of its three-dimensional Fermi-surface topology. An analogous result was obtained for ͑Ba, K͒Fe 2 As 2 , indicating that all layered iron-based superconductors exhibit generic behavior that is significantly different from that of the "high-T c " cuprates.

Temperature and angular dependence of the upper critical field in K2Cr3As3

“…The phenomenon of crossing of H ⊥ c2 (T ) and H c2 (T ), although being uncommon, was reported in several other systems including the quasi-1D organic superconductor (TMTSF) 2 PF 6 [34], iron-based chalcogenides [35][36][37], and the heavy-fermion superconductor UPt 3 [38]. Nevertheless, details of the H c2 (T ) crossing, which reflect the origin of the anisotropy reversal, differ from each other.…”

Intrinsic pinning by naturally occurring correlated defects in FeSe1−xTexsuperconductors

“…The main features of the normal state resistivity in samples of the β-phase have been described in the literature [19,20,21,22]. A metallic like behavior was reported for the Se rich end.…”

Angular-dependent upper critical field of overdoped Ba(Fe1−xNix)2Murphy1, Tanatar2, Graf3 et al. 2013Phys. Rev. B245150View full textAdd to dashboardCite

“…These high values may come from strong coupling nature of superconductivity in iron pnictides, or indeed reflect paramagnetic limiting at low temperatures as was suggested in several studies. 32,60,74 V. CONCLUSIONS By performing high angular resolution study of the upper critical field in two overdoped compositions of iron pnictide superconductor Ba(Fe 1−x Ni x ) 2 As 2 , we find clear deviations from the anisotropic Ginzburg-Landau form. Implementing linearization plot analysis of our and previously published data, we find clear deviations from the form only in the case of clean fully -gapped multi-band superconductors, such as NbSe 2 ang MgB 2 , but not in dirty MgB 2 and not clean KFe 2 As 2 .…”