Evidence of singlets in a 122-type Fe-based superconductor

POSTER

Abstract

Cuprate superconductors often show signature of Zhang-Rice singlet states in their photoemission spectral functions which are believed to play a role in their ground state properties. Here, we studied the core level spectra of a Fe-based superconductor, CaFe1.9Co0.1As2 (Tc = 15 K) in the 122-family employing high-resolution hard x-ray photoemission spectroscopy (HAXPES). While the As core level spectra show negligible change with doping and/or temperature, the Ca 2p HAXPES data show a decrease in surface-bulk difference with Co-doping compared to its parent compound, CaFe2As2. The peak position shifts gradually towards lower binding energies with cooling. Interestingly, the Fe 2p spectra show emergence of a new feature at a lower binding energy relative to the screened Fe 2p peak in the doped sample. The intensity of this feature enhances with the decrease in temperature. The property of this feature is very similar to the Zhang-Rice singlets observed in cuprates and the low energy screened feature in manganites. Emergence of this feature in the superconducting composition and its enhancement with the decrease in temperature suggests relevance of the underlying interactions in the ground state properties of these Fe-based superconductors.

*The authors acknowledge financial support under the India-DESY program and Department of Atomic Energy (DAE), Government of India (Project Identification No. RTI4003, DAE OM No. 1303/2/2019/R&D-II/DAE/2079 dated 11-02-2020). K.M. acknowledges financial assistance from DAE under the DAE-SRC-OI Award program.

Publication: R. P. Pandeya, A. P. Sakhya, S. Datta, T. Saha, G. De Ninno, R. Mondal, C. Schlueter, A. Gloskovskii, P. Moras, M. Jugovac, C. Carbone, A. Thamizhavel, and K. Maiti, Physical Review B 104, 094508 (2021).

Presenters

  • Ram Prakash Pandeya

    • Tata Institute of Fundamental Research

Authors

  • Ram Prakash Pandeya

    • Tata Institute of Fundamental Research

  • Anup Pradhan Sakhya

    • University of Central Florida

  • Sawani Datta

    • Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India

  • Tanusree Saha

    • Laboratory of Quantum Optics, University of Nova Gorica, 5001 Nova Gorica, Slovenia
    • university of Nova Gorica

  • Giovanni De Ninno

    • Laboratory of Quantum Optics, University of Nova Gorica, 5001 Nova Gorica, Slovenia
    • Elettra-Sincrotrone Trieste

  • Rajib Mondal

    • Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
    • UGC-DAE Consortium for Scientific Research, Kolkata Centre, Bidhannagar, Kolkata

  • Christoph Schlueter

    • Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
    • DESY, Petra III, Hamburg, Germany

  • Andrei Gloskovskii

    • Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
    • DESY, Petra III, Hamburg, Germany
    • DESY
    • Deutsches Elektronen-Synchrotron DESY, Germany

  • Paolo Moras

    • Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Area Science Park, I-34149 Trieste, Italy

  • Matteo Jugovac

    • Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Area Science Park, I-34149 Trieste, Italy

  • Carlo Carbone

    • Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Area Science Park, I-34149 Trieste, Italy

  • A Thamizhavel

    • Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
    • Tata Institute of Fundamental Research, Mumbai
    • Tata Institute of Fundamental Research

  • Kalobaran Maiti

    • Tata Inst of Fundamental Res