Collective Modes in SrTi<sub>1-<i>x</i></sub>Nb<i><sub>x</sub></i>O<sub>3</sub> Measured with meV-Resolution EELS

ORAL

Abstract

The emergence of superconductivity in low carrier solids does not follow the behavior of conventional BCS superconductivity. Niobium doped strontium titanate, SrTi1-xNbxO3, which becomes a superconductor at densities as low as 5.5×1017 cm-3 [1], is theorized to come about due to the hybridization of the longitudinal optic phonons with the plasmons. In this talk, I will present measurements of the collective charge excitations of SrTi1-xNbxO3 using momentum-resolved inelastic electron scattering (M-EELS). We observed a variety of acoustic and optic phonons in the range 0-200 meV that have been implicated in the superconducting pairing in this material. In addition, we observed an electronic mode at 25 meV that we identify as a valence plasmon from the Nb free carriers. I will discuss evidence for hybridization of these modes for different Nb concentration, x.

[1] X. Lin, Z. Zhu, B. Fauqué, and K. Behnia, Phys. Rev. X 3, 021002 (2013).

*This work was supported by the Gordon and Betty Moore Foundation's EPiQS Initiative through Grant GBMF - 4542 and by the National Science Foundation Graduate Research Fellowship under Grant No. DGE - 1746047.

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Presenters

  • Samantha Rubeck

    • University of Illinois at Urbana-Champaign
    • Department of Physics and Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign

Authors

  • Samantha Rubeck

    • University of Illinois at Urbana-Champaign
    • Department of Physics and Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign

  • Melinda Rak

    • University of Illinois at Urbana-Champaign
    • Department of Physics and Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign

  • Matteo Mitrano

    • University of Illinois at Urbana-Champaign
    • Department of Physics and Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign
    • Physics, University of Illinois at Urbana-Champaign

  • Ali Husain

    • University of Illinois at Urbana-Champaign
    • Department of Physics and Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign
    • Physics, University of Illinois at Urbana-Champaign

  • Jin Chen

    • University of Illinois at Urbana-Champaign

  • Alexander Edelman

    • University of Chicago

  • Peter B Littlewood

    • University of Chicago

  • Peter Abbamonte

    • University of Illinois, Urbana-Champaign
    • University of Illinois at Urbana-Champaign
    • Department of Physics and Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign