Field-dependent transport critical current in single crystals of Ba(Fe1-xTMx)(2)As-2 (TM = Co, Ni) superconductors

TitleField-dependent transport critical current in single crystals of Ba(Fe1-xTMx)(2)As-2 (TM = Co, Ni) superconductors
Publication TypeJournal Article
Year of Publication2010
AuthorsTanatar MA, Ni N, Bud'ko SL, Canfield PC, Prozorov R
Journal TitleSuperconductor Science & Technology
Volume23
Pages054002
Date Published05/02
ISBN Number0953-2048
Accession NumberISI:000277029800007
Keywordsvortices
Abstract

Critical current density was studied by direct electrical transport measurements in single crystals of Ba(Fe1-xTMx)(2)As-2 under magnetic fields up to 9 T. To understand the relation of the critical current to the structural transformations in the material, the electron doping level was controlled by the amount of TM = Co (underdoped x = 0.054 versus optimally doped x = 0.074) and by the nature of the dopant (optimally doped TM = Co versus TM = Ni). It is found that the suppression of the critical current density by the magnetic field is much slower for Ni and underdoped Co compositions than for an optimally doped Co composition. We relate this difference to the proximity to the orthorhombic/antiferromagnetic phase boundary in the T(x) phase diagram. Structural domains formed in this area of the phase diagram create favorable conditions for pinning and not only increase critical current densities, but also hamper the degradation of the critical current under magnetic field.

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