Disorder, critical currents, and vortex pinning energies in isovalently substituted BaFe2(As1-xPx)(2)

作者：Demirdis S^*; Fasano Y; Kasahara S; Terashima T; Shibauchi T; Matsuda Y; Konczykowski Marcin; Pastoriza H; van der Beek C J

来源：Physical Review B, 2013, 87(9): 094506.

DOI：10.1103/PhysRevB.87.094506

We present a comprehensive overview of vortex pinning in single crystals of the isovalently substituted iron-based superconductor BaFe2(As1-xPx)(2), a material that qualifies as an archetypical clean superconductor, containing only sparse strong pointlike pins [in the sense of C. J. van der Beek et al., Phys. Rev. B 66, 024523 (2002)]. Widely varying critical current values for nominally similar compositions show that flux pinning is of extrinsic origin. Vortex configurations, imaged using the Bitter decoration method, show less density fluctuations than those previously observed in charge-doped Ba(Fe1-xCox)(2)As-2 single crystals. Analysis reveals that the pinning force and energy distributions depend on the P content x. However, they are always much narrower than in Ba(Fe1-xCox)(2)As-2, a result that is attributed to the weaker temperature dependence of the superfluid density on approaching T-c in BaFe2(As1-xPx)(2). Critical current density measurements and pinning force distributions independently yield a mean distance between effective pinning centers (L) over bar similar to 90 nm, increasing with increasing P content x. This evolution can be understood as being the consequence of the P dependence of the London penetration depth. Further salient features are a wide vortex free "Meissner belt", observed at the edge of overdoped crystals, and characteristic chainlike vortex arrangements, observed at all levels of P substitution. DOI: 10.1103/PhysRevB.87.094506

• 出版日期2013-3-11
• 单位中国地震局