Superconductivity of underdoped PrFeAs(O,F) investigated via point-contact spectroscopy and nuclear magnetic resonance

Abstract

Underdoped PrFeAs(O,F), one of the less known members of the 1111 family of iron-based superconductors, was investigated in detail by means of transport, SQUID magnetometry, nuclear magnetic resonance (NMR) measurements and point-contact Andreev-reflection spectroscopy (PCARS). PCARS measurements on single crystals evidence the multigap nature of PrFeAs(O,F) superconductivity, shown to host at least two isotropic gaps, clearly discernible in the spectra, irrespective of the direction of current injection (i.e., along the ab planes or along the c axis). Additional features at higher energy can be interpreted as signatures of a strong electron-boson coupling, as demonstrated by a model which combines Andreev reflection with the Eliashberg theory. Magnetic resonance measurements in the normal phase indicate the lack of a magnetic order in underdoped PrFeAs(O,F), while ${}^{75}$As NMR spin-lattice relaxation results suggest the presence of significant electronic spin fluctuations, peaking above $T_c$ and expected to mediate the superconducting pairing.

12 pages, 9 figures. Title changed, minor amendments in the text

References in corpus (20)

• High-temperature superconductivity in iron-based materials
• Thorium-doping induced superconductivity up to 56 K in Gd1-xThxFeAsO
• Superconductivity at 25 K in hole doped $(L{a}_{1-x}S{r}_x)OFeAs$
• The electronic phase diagram of the LaO1-xFxFeAs superconductor
• Coexistence of static magnetism and superconductivity in SmFeAsO1-xFx as revealed by muon spin rotation
• ${}^{75}$As NMR studies of superconducting LaO${}_{0.9}$F${}_{0.1}$FeAs
• Microwave Penetration Depth and Quasiparticle Conductivity in PrFeAsO_1-y Single Crystals : Evidence for a Full-Gap Superconductor
• Spin-singlet superconductivity with multiple gaps in PrO0.89F0.11FeAs
• Effects of magnetism and doping on the electron-phonon coupling in BaFe${}_2$As${}_2$
• Superconductivity in LaFeAs${}_{1-x}$P${}_x$O: effect of chemical pressures and bond covalency
• High-pressure flux growth, structural, and superconducting properties of LnFeAsO (Ln = Pr, Nd, Sm) single crystals
• Magnetic-superconducting phase boundary of SmFeAsO${}_{1-x}$F${}_x$ studied via muon spin rotation: Unified behavior in a pnictide family
• Coexistence of two order parameters and a pseudogaplike feature in the iron-based superconductor LaFeAsO_(1-x)F_x
• Th substituted SmFeAsO: structural details and superconductivity with Tc above 50 K
• Synthesis, structural and transport properties of the hole-doped Superconductor Pr_{1-x}Sr_xFeAsO
• Emergence of Novel Antiferromagnetic Order Intervening between Two Superconducting Phases in LaFe(As_1-x_P_x_)O: 31P-NMR Studies
• High-$T_{\mathrm{c}}$ superconductivity in undoped ThFeAsN
• Point-contact spectroscopy in Co-doped CaFe2As2: nodal superconductivity and topological Fermi surface transition
• Slow magnetic fluctuations and superconductivity in fluorine-doped NdFeAsO
• Superconducting Order Parameter and Bosonic Mode in Hydrogen-Substituted NdFeAsO${}_{0.6}$H${}_{0.36}$ Revealed by Multiple Andreev Reflection Spectroscopy