Two-dimensional phase-fluctuating superconductivity in bulk crystalline NdO0.5F0.5BiS2

C. S. Chen; J. Küspert; I. Biało; J. Mueller; K. W. Chen; M. Y. Zou; D. G. Mazzone; D. Bucher; K. Tanaka; O. Ivashko; M. v. Zimmermann; Qisi Wang; Lei Shu; J. Chang

doi:10.1103/PhysRevB.109.054516

Two-dimensional phase-fluctuating superconductivity in bulk crystalline NdO0.5F0.5BiS2

C. S. Chen, J. Küspert, I. Biało, J. Mueller, K. W. Chen, M. Y. Zou, D. G. Mazzone, D. Bucher, K. Tanaka, O. Ivashko, M. v. Zimmermann, Qisi Wang, Lei Shu, J. Chang

DOI 10.1103/PhysRevB.109.054516 · Physical Review B

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Abstract

We present a combined growth and transport study of superconducting single-crystalline NdO0.5F0.5BiS2. Evidence of two-dimensional superconductivity with significant phase fluctuations of preformed Cooper pairs preceding the superconducting transition is reported. This result is based on three key observations. (1) The resistive superconducting transition temperature Tc (defined by resistivity ρ→0) increases with increasing disorder. (2) As T→Tc, the conductivity diverges significantly faster than what is expected from Gaussian fluctuations in two and three dimensions. (3) Non-Ohmic resistance behavior is observed in the superconducting state. Altogether, our observations are consistent with a temperature regime of phase-fluctuating superconductivity. The crystal structure with magnetic ordering tendencies in the NdO0.5F0.5 layers and (super)conductivity in the BiS2 layers is likely responsible for the two-dimensional phase fluctuations. As such, NdO0.5F0.5BiS2 falls into the class of unconventional “laminar” bulk superconductors that include cuprate materials and 4Hb−TaS2.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
NdO0.5F0.5BiS2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	3.5	Pressure not reported	zero_resistance
NdO0.5F0.5BiS2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	5	Pressure not reported	onset
CeO0.5F0.5BiS2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
Pr1.05O0.82F0.18Bi1.03S2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
Pr2-xCexCuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
La2-xSrxCuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
La1.875Ba0.125CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
NbN Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown