Superconductivity-induced optical anomaly in an iron arsenide

One of the central tenets of conventional theories of superconductivity, including most models proposed for the recently discovered iron-pnictide superconductors, is the notion that only electronic excitations with energies comparable to the superconducting energy gap are affected by the transition....

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Main Authors:	Charnukha, A., Popovich, P., Matiks, Y., Sun, D. L., Lin, C. T., Yaresko, A. N., Keimer, B., Boris, A. V.
Format:	Online
Language:	English
Published:	Nature Publishing Group 2011
Online Access:	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3080249/

id	pubmed-3080249
recordtype	oai_dc
spelling	pubmed-30802492011-05-12 Superconductivity-induced optical anomaly in an iron arsenide Charnukha, A. Popovich, P. Matiks, Y. Sun, D. L. Lin, C. T. Yaresko, A. N. Keimer, B. Boris, A. V. Article One of the central tenets of conventional theories of superconductivity, including most models proposed for the recently discovered iron-pnictide superconductors, is the notion that only electronic excitations with energies comparable to the superconducting energy gap are affected by the transition. Here, we report the results of a comprehensive spectroscopic ellipsometry study of a high-quality crystal of superconducting Ba0.68K0.32Fe2As2 that challenges this notion. We observe a superconductivity-induced suppression of an absorption band at an energy of 2.5 eV, two orders of magnitude above the superconducting gap energy 2Δ≈20 meV. On the basis of density functional calculations, this band can be assigned to transitions from As-p to Fe-d orbitals crossing the Fermi level. We identify a related effect at the spin-density wave transition in parent compounds of the 122 family. This suggests that As-p states deep below the Fermi level contribute to the formation of the superconducting and spin-density wave states in the iron arsenides. Nature Publishing Group 2011-03-01 /pmc/articles/PMC3080249/ /pubmed/21364558 http://dx.doi.org/10.1038/ncomms1223 Text en Copyright © 2011, Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved. http://creativecommons.org/licenses/by-nc-nd/3.0/ This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/
repository_type	Open Access Journal
institution_category	Foreign Institution
institution	US National Center for Biotechnology Information
building	NCBI PubMed
collection	Online Access
language	English
format	Online
author	Charnukha, A. Popovich, P. Matiks, Y. Sun, D. L. Lin, C. T. Yaresko, A. N. Keimer, B. Boris, A. V.
spellingShingle	Charnukha, A. Popovich, P. Matiks, Y. Sun, D. L. Lin, C. T. Yaresko, A. N. Keimer, B. Boris, A. V. Superconductivity-induced optical anomaly in an iron arsenide
author_facet	Charnukha, A. Popovich, P. Matiks, Y. Sun, D. L. Lin, C. T. Yaresko, A. N. Keimer, B. Boris, A. V.
author_sort	Charnukha, A.
title	Superconductivity-induced optical anomaly in an iron arsenide
title_short	Superconductivity-induced optical anomaly in an iron arsenide
title_full	Superconductivity-induced optical anomaly in an iron arsenide
title_fullStr	Superconductivity-induced optical anomaly in an iron arsenide
title_full_unstemmed	Superconductivity-induced optical anomaly in an iron arsenide
title_sort	superconductivity-induced optical anomaly in an iron arsenide
description	One of the central tenets of conventional theories of superconductivity, including most models proposed for the recently discovered iron-pnictide superconductors, is the notion that only electronic excitations with energies comparable to the superconducting energy gap are affected by the transition. Here, we report the results of a comprehensive spectroscopic ellipsometry study of a high-quality crystal of superconducting Ba0.68K0.32Fe2As2 that challenges this notion. We observe a superconductivity-induced suppression of an absorption band at an energy of 2.5 eV, two orders of magnitude above the superconducting gap energy 2Δ≈20 meV. On the basis of density functional calculations, this band can be assigned to transitions from As-p to Fe-d orbitals crossing the Fermi level. We identify a related effect at the spin-density wave transition in parent compounds of the 122 family. This suggests that As-p states deep below the Fermi level contribute to the formation of the superconducting and spin-density wave states in the iron arsenides.
publisher	Nature Publishing Group
publishDate	2011
url	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3080249/
_version_	1611449951339937792

Superconductivity-induced optical anomaly in an iron arsenide

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