1. Unusual nodal behaviors of the superconducting gap in the iron-based superconductor Ba(Fe$_{0.65}$Ru$_{0.35}$)$_2$As$_2$: Effects of spin-orbit coupling
- Author
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Liu, L., Okazaki, K., Yoshida, T., Suzuki, H., Horio, M., Ambolode II, L. C. C., Xu, J., Ideta, S., Hashimoto, M., Lu, D. H., Shen, Z. -X., Ota, Y., Shin, S., Nakajima, M., Ishida, S., Kihou, K., Lee, C. H., Iyo, A., Eisaki, H., Mikami, T., Kakeshita, T., Yamakawa, Y., Kontani, H., Uchida, S., and Fujimori, A.
- Subjects
Condensed Matter - Superconductivity - Abstract
We have investigated the superconducting gap of optimally doped Ba(Fe$_{0.65}$Ru$_{0.35}$)$_2$As$_2$ by angle-resolved photoemission spectroscopy (APRES) using bulk-sensitive 7 eV laser and synchrotron radiation. It was found that the gap is isotropic in the $k_x$-$k_y$ plane both on the electron and hole Fermi surfaces (FSs). The gap magnitudes of two resolved hole FSs show similar $k_z$ dependences and decrease as $k_z$ approaches $\sim$ 2$\pi$/$c$ (i.e., around the Z point) unlike the other Fe-based superconductors reported so far, where the superconducting gap of only one hole FS shows a strong $k_z$ dependence. This unique gap structure can be understood in the scenario that the $d_{z^2}$ orbital character is mixed into both hole FSs due to the finite spin-orbit coupling between almost degenerate FSs and is reproduced by calculations within the random phase approximation including the spin-orbit coupling.
- Published
- 2016
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