AUTHOR=Yoshida Teppei , Ideta Shin-ichiro , Nishi Ichiro , Fujimori Atsushi , Yi Ming , Moore Rob , Mo Sung-Kwan , Lu Donghui , Shen Zhi-Xun , Hussain Zahid , Kihou Kunihiro , Lee C. H , Iyo Akira , Eisaki Hiroshi , Harima Hisatomo 

TITLE=Orbital character and electron correlation effects on two- and three-dimensional Fermi surfaces in KFe2As2 revealed by angle-resolved photoemission spectroscopy

JOURNAL=Frontiers in Physics

VOLUME=2

YEAR=2014

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2014.00017

DOI=10.3389/fphy.2014.00017

ISSN=2296-424X

ABSTRACT=<p>We have investigated orbital character and electron correlation effects on Fermi surfaces in the hole-overdoped iron pnictide superconductor KFe<sub>2</sub>As<sub>2</sub>, which shows a low <italic>T</italic><sub><italic>c</italic></sub> of ~4 K, by angle-resolved photoemission spectroscopy. From the polarization-dependence of the ARPES spectra, we have determined the orbital character of each Fermi surface. Electron mass renormalization of each band is quantitatively consistent with de Haas-van Alphen results. The outer β and middle ζ Fermi surfaces show large renormalization factor of <italic>m</italic><sup>*</sup>/<italic>m</italic><sub><italic>b</italic></sub> ~6–7, while the inner α Fermi surface has a smaller factor <italic>m</italic><sup>*</sup>/<italic>m</italic><sub><italic>b</italic></sub> ~2. Middle hole Fermi surface ζ has strong three-dimensionality compared to other Fermi surfaces, indicating the <italic>d</italic><sub>3<italic>z</italic>2–<italic>r</italic>2</sub> orbital character, which may be related to the “octet-line nodes” recently observed by laser ARPES. The observed orbital-dependent mass renormalization would give constraints on the pairing mechanism with line nodes of this system.</p>