Point contact spectroscopy in Fe-based superconductors: recent advancements and future challenges

Abstract

Iron-based superconductors (FeSC) present an unprecedented variety of features both in the superconducting and in the normal state. Different families differ in the value of the critical temperature, in the shape of the Fermi surface, in the existence or absence of quasi-nesting conditions, in the range of doping in which the antiferromagnetic (AFM) and the superconducting phase coexist and in the structure of the order parameter in the reciprocal space, and so on. In this paper the most important results of point-contact spectroscopy (PCS) in Fe-based superconductors are reviewed, and the most recent advances are described with the aim to discuss the future perspectives and challenges of this spectroscopic technique in the characterization of the superconducting properties of these complex compounds. One of the main challenges, faced so far only by a few researchers in the PCS field, is to fully explore the phase diagram of these materials, as a function of doping or pressure, to understand the interplay between superconductivity and magnetism, the effect of intrinsic or extrinsic inhomogeneities, the role of spin fluctuations (SFs) in the pairing, the symmetry and the structure of the order parameter(s).

12 pages, 4 figures

References in corpus (22)

• Superconductivity at 43 K in Samarium-arsenide Oxides $SmFeAs{O}_{1-x}{F}_x$
• High-temperature superconductivity in iron-based materials
• Electronic Structure and Doping in BaFe${}_2$As${}_2$ and LiFeAs: Density Functional Calculations
• Magnetism in Fe-based superconductors
• Evidence for nodal superconductivity in LaFePO
• The role of critical current on point contact Andreev Reflection spectrum between a normal metal and a superconductor
• Evidence for two-gap superconductivity in (Ba,K)Fe_2As_2 by directional point contact Andreev reflection spectroscopy
• Homogeneous vs. inhomogeneous coexistence of magnetic order and superconductivity probed by NMR in Co and K doped iron pnictides
• Possible three dimensional nodes in the $s\pm$ superconducting gap of BaFe${}_2$(As${}_{1-x}$P${}_x$)${}_2$
• Observation of Andreev bound state and multiple energy gaps in the non-centrosymmetric superconductor BiPd
• A doping dependent specific heat study of the superconducting gap in Ba(Fe${}_{1-x}$Co${}_x$)${}_2$As${}_2$
• 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
• Effect of annealing on the specific heat of Ba(Fe1-xCox)2As2
• Evidence for gap anisotropy in CaC6 from directional point-contact spectroscopy
• Point contact Andreev reflection spectroscopy of NdFeAsO_0.85
• Evidence of a universal and isotropic 2Δ/kBTC ratio in 122-type iron pnictide superconductors over a wide doping range
• Phase-incoherent superconducting pairs in the normal state of Ba(Fe${}_{1-x}$Co${}_x$)${}_2$As${}_2$
• Effects of isoelectronic Ru substitution at the Fe site on the energy gaps of optimally F-doped SmFeAsO
• Determination of the pairing state in iron-based superconductors through neutron scattering
• Point-contact spectroscopy in Co-doped CaFe2As2: nodal superconductivity and topological Fermi surface transition

Cited by in corpus (6)

• Electrical and Thermal Transport in Antiferromagnet-Superconductor Junctions
• Doping and critical-temperature dependence of the energy gaps in Ba(Fe_{1-x}Co_x)_2As_2 thin films
• Evidence of triplet superconductivity in Bi/Ni bilayers: Theoretical analysis of point contact Andreev reflection spectroscopy results
• Single 20meV boson mode in KFe2As2 detected by point-contact spectroscopy
• Superconductivity of Co-Doped CaKFe4As4 Investigated via Point-Contact Spectroscopy and London Penetration Depth Measurements
• Exploring unconventional superconductivity in PdTe via Point Contact Spectroscopy