| AVS 63rd International Symposium & Exhibition | |
| Scanning Probe Microscopy Focus Topic | Monday Sessions |
| Session SP+2D+AS+NS+SS-MoA |
| Session: | Probing Topological States And Superconductivity |
| Presenter: | Qiang Zou, Oak Ridge National Laboratory |
| Authors: | Q. Zou, Oak Ridge National Laboratory Z. Wu, Oak Ridge National Laboratory Q. Zheng, Oak Ridge National Laboratory S. RajputƗ, Oak Ridge National Laboratory D.S. Parker, Oak Ridge National Laboratory A.S. Sefat, Oak Ridge National Laboratory Z. Gai, Oak Ridge National Laboratory |
| Correspondent: | Click to Email |
By hole or electron doping of the parent iron-based BaFe2As2 compound, the high-transition temperature superconductivity emerges from the suppression of the antiferromagnetic order. 1 It was widely reported that thermal-annealing significantly improves some superconducting characteristics in Ba(Fe1−xCox )2As2, including Tc 2 The microscopic origin of such effect is still an open question. To make a connection between the global and the microscopic behavior of the materials, we did a comparison measurement on the pair of well-characterized x, we call ‘ as-grown’ vs ‘annealed’ Ba(Fe1-xCox)2As2 crystals, and using low temperature scanning tunneling microscopy and spectroscopy (STM/S). The superconducting gap maps deducted from the dI/dV maps were compared. The gap width distribution of the as-grown sample are obviously narrower than that of the annealed one. The coherent peak position also shifted to higher value for the annealed sample. The corresponding reduced-gaps of 2Δ/kbTc1 are about 2.3 and 5.4 for the as-grown and annealed crystals, respectively. The difference of the reduced-gaps indicates that the pairing strength of the annealed crystal is stronger than the as-grown one.
This research was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Science and Engineering Division . A portion of this research was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility.
Reference
1. Stewart, G. R. (2011). “Superconductivity in iron compounds”, Reviews of Modern Physics, 83(4), 1589.
2. Gofryk, K., et al. "Effect of annealing on the specific heat of Ba(Fe1−xCox)2As2" Physical Review B, 83(6), 064513