Specific-heat discontinuityΔCvs.Tcin annealed Ba(Fe1−x

Effect of interlayer coupling on the coexistence of antiferromagnetism and superconductivity in Fe pnictide superconductors: A study ofCa0.74(1)La0.26(1Jiang1, Liu2, Schütt3 et al. 2016Phys. Rev. B232181View full textAdd to dashboardCite

“…By the equal entropy construction shown in Fig. 2(b), the heat capacity jump ∆C p /T | Tc is 6.7 mJ/moleFe-K 2 at T c ≈16 K. This value follows the Budko-NiCanfield(BNC) log-log plot quite well 13 , suggesting that C p ∝ T 3 c . Since most of the FBS superconductors follow this BNC scaling 14 , this may suggest an S± pairing symmetry in CaLa112.…”

Combined effects of post-growth thermal treatment and chemical substitution on physical properties of CaFe₂As₂

“…Given previous observations of only small shifts in the magnetic/structural transition temperatures of BaFe 2 As 2 samples and of the superconducting transition in Ba(Fe 1−x Co x ) 2 As 2 , as well as of sharpenings of their signatures in thermodynamic and transport data, after postgrowth thermal treatment (Rotundu et al, 2010;Gofryk et al, 2011;Kim et al, 2012a), it is necessary to undertake a systematic study of the effects of postgrowth thermal treatment of FeAs-grown single crystals of both parent and transition metal substituted CaFe 2 As 2 .…”

“…Returning to the initial motivations for this study: given that annealing/quenching of as-grown samples seems to lead to small changes in the transition temperatures of BaFe 2 As 2 -based compounds (Rotundu et al, 2010;Gofryk et al, 2011;Kim et al, 2012a) and given that CaFe 2 As 2 is much more pressure or strain sensitive than BaFe 2 As 2 , it is worth exploring the implications of our current findings. If we speculate that a similar width of formation exists in BaFe 2 As 2 (or for that matter SrFe 2 As 2 ) and that low-temperature annealing/quenching can lead to similar effects as those we present here, then, based on the existing P -T phase diagrams (Colombier et al, 2009), an effective pressure of ∼ 0.4 GPa on BaFe 2 As 2 or SrFe 2 As 2 would lead only to shifts in transition temperature of a few K, consistent with what has been observed.…”

“…In order for these larger crystals to manifest a AFM/ORTH phase transition similar to that seen in the smaller Sn-grown crystal, they were annealed at 500 • C (a temperature similar to the decanting temperature of the Sn-grown samples) (Goldman et al, 2009) for 24 h and then quenched to room temperature. Given previous observations of small shifts in the AFM/ORTH phase transition temperatures of BaFe 2 As 2 samples and of the superconducting transition in doped BaFe 2 As 2 , as well as of sharpenings of their signatures in thermodynamic and transport data, after post-growth thermal treatment (Rotundu et al, 2010;Gofryk et al, 2011;Kim et al, 2012a), it is necessary to undertake a systematic study of the effects of postgrowth thermal treatment of FeAs-grown single crystals of CaFe 2 As 2 . In order to characterize and understand the effects of annealing/quenching, as well as the nature of the low-temperature state, a wide variety of thermodynamic, transport, microscopic, and spectroscopic measurements have been performed .…”

Tunnel-diode resonator and nuclear magnetic resonance studies of low-dimensional magnetic and superconducting systems

“…For example, studies of the superconducting gap structure from penetration depth [126][127][128], directional heat transport [129], and heat capacity [130][131][132][133] as a function of doping suggested full gap at optimal doping universally in BaT M 122 and BaK122 [134], evolving towards strongly anisotropic and nodal in the under-doped and overdoped regimes. A similar trend is found in the other families of iron pnictides, e.g.…”