2012/11/20 by John Timmerwilke, Timmerwilke, John, E Kim +9
Materials Science · Physics and Astronomy · #FOS: Physical sciences #Iron-based superconductors research #Physics of Superconductivity and Magnetism #Rare-earth and actinide compounds #Strongly Correlated Electrons (cond-mat.str-el) #Superconductivity (cond-mat.supr-con)
paper · pdf · doi:10.48550/arxiv.1211.4659
openalex publication_date 2012/11/20 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
Point contact spectroscopy (PCS) is a technique which can reveal the size and symmetry of a superconducting gap (Δ) and is especially useful for new materials such as the iron-based superconductors. PCS is usually employed in conjunction with the extended Blonder-Tinkham-Klapwijk (BTK) model which is used to extract information such as the existence of nodes in Δ from PCS data obtained on unconventional superconductors. The BTK model uses a dimensionless parameter Z to quantify the barrier strength across a normal metal - superconductor junction. We have used a unique feature of PCS which allows variation of Z to obtain crucial information about Δ. We report our Z-dependent, a-b plane PCS measurements on single crystals of the iron-based superconductor BaFe2-xCoxAs2. Our measurements show that BaFe2-xCoxAs2 (x=0.148) is a superconductor with two gaps which does not contain any nodes. The Z dependent point contact spectra rule out a pure d symmetry and the gaps at optimal doping have negligible anisotropy.