Point contact Andreev reflection spectroscopy of NdFeAsO_0.85

Abstract

The newly discovered oxypnictide family of superconductors show very high critical temperatures of up to 55K. Whilst there is growing evidence that suggests a nodal order parameter, point contact Andreev reflection spectroscopy can provide crucial information such as the gap value and possibly the number of energy gaps involved. For the oxygen deficient NdFeAsO0.85 with a Tc of 45.5K, we show that there is clearly a gap value at 4.2K that is of the order of 7meV, consistent with previous studies on oxypnictides with lower Tc. Additionally, taking the spectra as a function of gold tip contact pressure reveals important changes in the spectra which may be indicative of more complex physics underlying this structure.

11 pages, 3 figures. New references included, extra discussion. This version is accepted in Superconductor Science and Technology

References in corpus (7)

• Superconductivity and Phase Diagram in the Iron-based Arsenic-oxides ReFeAsO1-delta (Re = rare earth metal) without F-Doping
• Anisotropy of superconducting single crystal SmFeAsO_(0.8)F_(0.2) studied by torque magnetometry
• Superconducting energy gap and c-axis plasma frequency of (Nd,Sm)O0.82F0.18FeAs superconductors from infrared ellipsometry
• X-ray spectra and electronic structure of FeAs superconductors
• Theory of point contact spectroscopy in electron-doped cuprates
• Impurity resonance states in electron-doped high T_c superconductors
• Magnetic measurements and 57Fe Mossbauer spectroscopy in oxygen deficient SmFeAsO0.85

Cited by in corpus (12)

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• NMR relaxation rate in superconducting pnictides: extended $s_{\pm }$ scenario
• Evidence for two-gap superconductivity in (Ba,K)Fe_2As_2 by directional point contact Andreev reflection spectroscopy
• Scanning tunneling spectroscopy of SmFeAsO0.85: Possible evidence for d-wave order parameter symmetry
• Nodal Superconductivity with Multiple Gaps in SmFeAsO${}_{0.9}$F${}_{0.1}$
• Possible two-gap superconductivity in NdFeAs(O,F) probed by point-contact Andreev-reflection spectroscopy
• Coexistence of two order parameters and a pseudogaplike feature in the iron-based superconductor LaFeAsO_(1-x)F_x
• Point-contact Andreev-reflection spectroscopy in ReFeAsO_{1-x}F_x (Re = La, Sm): Possible evidence for two nodeless gaps
• Thermal properties of SmFeAs(O1-xFx) as probe of the interplay between electrons and phonons
• Pairing symmetry and properties of iron-based high temperature superconductors
• Investigation of Superconducting Gap Structure in TbFeAsO${}_{0.9}$F${}_{0.1}$ using Point Contact Andreev Reflection
• Point-contact spectroscopy in Co-doped CaFe2As2: nodal superconductivity and topological Fermi surface transition