Low work function in the 122-family of iron-based superconductors

H. Pfau, H. Soifer, J. A. Sobota, A. Gauthier, C. R. Rotundu, J. C. Palmstrom, I. R. Fisher, G.-Y. Chen, H.-H. Wen, Z.-X. Shen, and P. S. Kirchmann
Phys. Rev. Materials 4, 034801 – Published 4 March 2020

Abstract

We determine the work functions of the iron arsenic compounds AFe2As2 (A=Ca,Ba,Cs) using photoemission spectroscopy to be 2.7 eV for CaFe2As2, 1.8 eV for BaFe2As2, and 1.3 eV for CsFe2As2. The work functions of these 122 iron-based superconductors track those of the elementary metal A but are substantially smaller. The most likely explanation of this observation is that the cleaving surface exposes only half an A-layer. The low work function and good photoemission cross section of BaFe2As2 and CsFe2As2 enable photoemission even from a common white LED light.

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  • Received 25 October 2019
  • Accepted 13 January 2020

DOI:https://doi.org/10.1103/PhysRevMaterials.4.034801

©2020 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

H. Pfau1,2,*, H. Soifer2,3, J. A. Sobota2,4, A. Gauthier2,4, C. R. Rotundu2, J. C. Palmstrom2,4, I. R. Fisher2,4, G.-Y. Chen5, H.-H. Wen5, Z.-X. Shen2,4,6, and P. S. Kirchmann2,†

  • 1Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
  • 2Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
  • 3Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 4R73 7+ 8Q, Israel
  • 4Geballe Laboratory for Advanced Materials, Department of Applied Physics, Stanford University, Stanford, California 94305, USA
  • 5Center for Superconducting Physics and Materials, National Laboratory of Solid State Microstructures and Department of Physics, National Center of Microstructures and Quantum Manipulation, Nanjing University, Nanjing 210093, China
  • 6Department of Physics, Stanford University, Stanford, California, USA

  • *hpfau@lbl.gov
  • kirchman@stanford.edu

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Vol. 4, Iss. 3 — March 2020

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