Orbital-Independent Superconducting Gaps in Iron Pnictides.

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Bibliographic Details
Title: Orbital-Independent Superconducting Gaps in Iron Pnictides.
Authors: Shimojima, T., Sakaguchi, F., Ishizaka, K., Ishida, Y., Kiss, T., Okawa, M., Togashi, T., Chen, C.-T., Watanabe, S., Arita, M., Shimada, K., Namatame, H., Taniguchi, M., Ohgushi, K., Kasahara, S., Terashima, T., Shibauchi, T., Matsuda, Y., Chainani, A., Shin, S.
Source: Science (pre-March 2025). 4/29/2011, Vol. 332 Issue 6029, p564-567. 4p.
Subjects: Superconductivity, Atomic orbitals, Physics experiments, Fermi surfaces, Photoelectron spectroscopy, Photoemission, Spectrum analysis, Iron compounds, Antiferromagnetism, Nuclear spin
Abstract: The origin of superconductivity in the iron pnictides has been attributed to antiferromagnetic spin ordering that occurs in close combination with a structural transition, but there are also proposals that link superconductivity to orbital ordering. We used bulk-sensitive laser angle-resolved photoemission spectroscopy on BaFe2(As0.65P0.35)2 and Ba0.6K0.4Fe2As2 to elucidate the role of orbital degrees of freedom on the electron-pairing mechanism. In strong contrast to previous studies, an orbital-independent superconducting gap magnitude was found for the hole Fermi surfaces. Our result is not expected from the superconductivity associated with spin fluctuations and nesting, but it could be better explained invoking magnetism-induced interorbital pairing, orbital fluctuations, or a combination of orbital and spin fluctuations. Regardless of the interpretation, our results impose severe constraints on theories of iron pnictides. [ABSTRACT FROM AUTHOR]
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Database: Psychology and Behavioral Sciences Collection
Description
Abstract:The origin of superconductivity in the iron pnictides has been attributed to antiferromagnetic spin ordering that occurs in close combination with a structural transition, but there are also proposals that link superconductivity to orbital ordering. We used bulk-sensitive laser angle-resolved photoemission spectroscopy on BaFe2(As0.65P0.35)2 and Ba0.6K0.4Fe2As2 to elucidate the role of orbital degrees of freedom on the electron-pairing mechanism. In strong contrast to previous studies, an orbital-independent superconducting gap magnitude was found for the hole Fermi surfaces. Our result is not expected from the superconductivity associated with spin fluctuations and nesting, but it could be better explained invoking magnetism-induced interorbital pairing, orbital fluctuations, or a combination of orbital and spin fluctuations. Regardless of the interpretation, our results impose severe constraints on theories of iron pnictides. [ABSTRACT FROM AUTHOR]
ISSN:00368075
DOI:10.1126/science.1202150