Upper and lower critical magnetic fields of superconducting NdFeAsO1−xFx single crystals studied by Hall-probe magnetization and specific heat

Z. Pribulova; T. Klein; J. Kacmarcik; C. Marcenat; M. Konczykowski; S. L. Bud’ko; M. Tillman; P. C. Canfield

doi:10.1103/PhysRevB.79.020508

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Upper and lower critical magnetic fields of superconducting NdFeAsO1−xFx single crystals studied by Hall-probe magnetization and specific heat

Z. Pribulova, T. Klein, J. Kacmarcik, C. Marcenat, M. Konczykowski, S. L. Bud’ko, M. Tillman, P. C. Canfield

DOI 10.1103/PhysRevB.79.020508 · Physical Review B

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Abstract

The upper and lower critical fields have been deduced from specific heat and Hall-probe magnetization measurements in nonoptimally doped Nd(O,F)FeAs single crystals (Tc∼32–35 K). The anisotropy of the penetration depth (Γλ) is temperature independent and on the order of 4.0±1.5. Similarly specific-heat data lead to an anisotropy of the coherence length Γξ∼5.5±1.5 close to Tc. Our results suggest the presence of rather large thermal fluctuations and the existence of a vortex liquid phase over a broad temperature range (∼5 K large at 2 T).

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
NdFeAsO1-xFx Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	33.5	Pressure not reported	midpoint
NdFeAsO1-xFx Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	34	Pressure not reported	onset
NdFeAsO1-xFx Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	50	Pressure not reported	onset
YBa2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
Ba1-xKxBiO3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	32	Pressure not reported	unknown
MgB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	39	Pressure not reported	unknown