Irreversibility line and flux pinning properties in iron-based high-Tc superconductor SmFeAsO0.85

Density effect on critical current density and flux pinning properties of polycrystalline SmFeAsO1 −xFxsuperconductor

“…At the fields near B max , the plots are scattered and located between the curves of surface pinning and normal point pinning. This result is similar to [28]. It is possible that the grain surfaces of the well-connected areas act as pinning centres for intergranular J c in low fields.…”

“…(2) The J cm (B) curves of samples B-F show a peak effect at t = 0.4 and 0.7 similar to [35]. The peak effect in J cm (B) was also observed in the oxygen deficient SmFeAsO 0.85 sample prepared by the high-pressure method [18] and (Ba, K)Fe 2 As 2 [37], but was absent for F-doped samples in [28][29][30]. Several reports suggest that the peak effect can be explained by the collective pinning and creep model [29,38,39].…”

“…The cracks, rare earth oxides and Fe-As wetting phase on the grain boundaries of SmFeAsO 1−x F x superconductor were investigated and proved to be detrimental to intergranular current flow [25,27]. So far there have only been a few reports [28][29][30] concerning the flux pinning mechanism in the REFeAs(O, F) superconductors, and no work related to the influence of sample density. In this paper, we prepared a group of polycrystalline SmFeAsO 1−x F x superconductors with different sample densities and comparatively investigated the density effect on superconductivity in detail.…”

Critical current density and vortex pinning mechanism of Lix(NH3)yFe2Te${}_{1.2}$Se${}_{0.8}$ single crystals

“…As shown in figure 4(c), the temperature dependence of m ( ) H T 0 irr agrees well with the theoretical fitting based on the flux creep model and the obtained parameters are K=40(1), m=1.9(1), and γ=0.20 (3). The values of m and γ are similar to those in Hg-based cuprate superconductors and SmFeAsO 0.85 [37,38].…”

Vortex dynamics and irreversibility line in optimally doped SmFeAsO0.8F0.2from ac suscept

“…Those measurements allow to further check the validity of the theories used to model the mixed state of cuprate materials and, in particular, the vortices motion and its relationship with the possible pinning mechanisms. 11 Several works reporting magnetoresistance, [12][13][14] modulated microwave absorption 15 and dc magnetization [16][17][18][19] examining the flux line lattice dynamics in 1111 oxy-pnictides have al-ready been published in the last two years. To our knowledge, no study of the flux line lattice by means of ac susceptibility measurements has been published yet.…”