1. NSLS-II Seminar

    "Laser ARPES studies on iron-pnictide superconductors"

    Presented by Walid Malaeb, Institute for Solid State Physics (ISSP), University of Tokyo, Japan

    Monday, September 9, 2013, 10 am
    Seminar Room, Bldg. 725

    Hosted by: Ignace Jarrige

    Angle-resolved photoemission spectroscopy (ARPES) is considered as the most powerful technique in directly probing the electronic structure of solids. As an example, iron-based superconductors especially the compound Ba1-xKxFe2As2 (BaK) have been extensively studied by ARPES. In most of these studies, synchrotron radiation or gas discharge lamps have been used as a light source and many aspects of the electronic structure of iron-pnictides including BaK have been uncovered, however there are still some issues to be resolved. For example, there is still little consensus on the superconducting (SC) gaps and their doping evolution in BaK. We have approached this problem using Laser ARPES which has some advantages over other light sources like an enhanced bulk sensitivity and ultra-high energy resolution. In this talk, I will briefly describe our Laser ARPES systems at ISSP [1] and proceed to show our main Laser ARPES results on BaK covering a wide doping range [2,3,4]. Particularly, I will focus on the doping evolution of the SC gaps and the significance of each of the orbital components of the Fermi surface sheets in this compound contrasting our results with those of other ARPES groups and with the available theoretical models on iron-pnictides. References [1] T. Kiss et al., Rev. Sci. Instrum. 79, 023106 (2008). [2] W. Malaeb et al., Phys. Rev. B 86, 165117 (2012). [3] K. Okazaki et al., Science 337, 1314 (2012). [4] Y. Ota, arXiv: 1307.7922. * malaeb@issp.u-tokyo.ac.jp