By means of infrared spectroscopy, we determine the temperature-doping phase diagram of the Fano effect for the in-plane Fe-As stretching mode in Ba1-xKxFe2As2. The Fano parameter 1/q(2), which is a measure of the phonon coupling to the electronic particle-hole continuum, shows a remarkable sensitivity to the magnetic and structural orderings at low temperatures. Most strikingly, at elevated temperatures in the paramagnetic tetragonal state we observe a linear correlation between 1/q(2) and the superconducting critical temperature T-c. Based on theoretical calculations and symmetry considerations, we identify the relevant interband transitions that are coupled to the Fe-As mode. In particular, we show that a sizable xy orbital component at the Fermi level is fundamental for the Fano effect and, thus, possibly also for the superconducting pairing.
Scaling of the Fano Effect of the In-Plane Fe-As Phonon and the Superconducting Critical Temperature in Ba1-xKxFe2As2 / Xu, B.; Cappelluti, E.; Benfatto, L.; Mallett, B. P. P.; Marsik, P.; Sheveleva, E.; Lyzwa, F.; Wolf, Th.; Yang, R.; Qiu, X. G.; Dai, Y. M.; Wen, H. H.; Lobo, R. P. S. M.; Bernhard, C.. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 122:21(2019). [10.1103/PhysRevLett.122.217002]
Scaling of the Fano Effect of the In-Plane Fe-As Phonon and the Superconducting Critical Temperature in Ba1-xKxFe2As2
Cappelluti E.;Benfatto L.;
2019
Abstract
By means of infrared spectroscopy, we determine the temperature-doping phase diagram of the Fano effect for the in-plane Fe-As stretching mode in Ba1-xKxFe2As2. The Fano parameter 1/q(2), which is a measure of the phonon coupling to the electronic particle-hole continuum, shows a remarkable sensitivity to the magnetic and structural orderings at low temperatures. Most strikingly, at elevated temperatures in the paramagnetic tetragonal state we observe a linear correlation between 1/q(2) and the superconducting critical temperature T-c. Based on theoretical calculations and symmetry considerations, we identify the relevant interband transitions that are coupled to the Fe-As mode. In particular, we show that a sizable xy orbital component at the Fermi level is fundamental for the Fano effect and, thus, possibly also for the superconducting pairing.File | Dimensione | Formato | |
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