Scaling of the Fano effect of the in-plane Fe-As phonon and the superconducting critical temperature in ${\mathrm{Ba}}_{1\ensuremath{-}x}{\mathrm{K}}_{x}{\mathrm{Fe}}_{2}{\mathrm{As}}_{2}$

Xu, Bing; Cappelluti, E.; Benfatto, Larra; Mallett, Benjamin P. P.; Marsik, Premysl; Sheveleva, Evgeniia; Lyzwa, Fryderyk; Wolf, Thomas; Yang, Rui; Qiu, X. G.; Dai, Y. M.; Wen, H. H.; Lobo, R. P. S. M.; Bernhard, Christian

doi:10.1103/PhysRevLett.122.217002

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Scaling of the Fano effect of the in-plane Fe-As phonon and the superconducting critical temperature in ${\mathrm{Ba}}_{1\ensuremath{-}x}{\mathrm{K}}_{x}{\mathrm{Fe}}_{2}{\mathrm{As}}_{2}$

Xu, Bing University of Fribourg, Department of Physics and Fribourg Center for Nanomaterials, Fribourg, Switzerland
Cappelluti, E. Istituto di Struttura della Materia, Trieste, Italy
Benfatto, Larra ISC-CNR and Department of Physics, Sapienza University of Rome, Italy
Mallett, Benjamin P. P. University of Fribourg, Department of Physics and Fribourg Center for Nanomaterials, Fribourg, Switzerland - The Photon Factory, Department of Physics, University of Auckland, New Zealand
Marsik, Premysl University of Fribourg, Department of Physics and Fribourg Center for Nanomaterials, Fribourg, Switzerland
Sheveleva, Evgeniia University of Fribourg, Department of Physics and Fribourg Center for Nanomaterials, Fribourg, Switzerland
Lyzwa, Fryderyk University of Fribourg, Department of Physics and Fribourg Center for Nanomaterials, Fribourg, Switzerland
Wolf, Thomas Institute of Solid State Physics, Karlsruhe Institute of Technology, Germany
Yang, Rui Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
Qiu, X. G. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
Dai, Y. M. National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, China
Wen, H. H. National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, China
Lobo, R. P. S. M. LPEM, ESPCI Paris, PSL University, CNRS, Paris, France - Sorbonne Université, CNRS, LPEM, Paris, France
Bernhard, Christian University of Fribourg, Department of Physics and Fribourg Center for Nanomaterials, Fribourg, Switzerland

29.05.2019

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Physical Review Letters. - 2019, vol. 122, no. 21, p. 217002

English 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=q2, 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=q2 and the superconducting critical temperature Tc. 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.

Faculty

Faculté des sciences et de médecine

Department

Département de Physique

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