Probing Finite-Momentum Charge Collective Modes in Electron Doped SrTiO<sub>3 </sub>

ORAL

Abstract

Electron doped strontium titanate, SrTiO3, becomes a bulk superconductor at carrier densities as low as 5.5×1017 cm-3. The pairing mechanism in this dilute material, which is unconventional and widely debated, has recently been explained in terms of hybridization between the longitudinal optic phonons and the electronic plasmon collective modes. Using momentum-resolved inelastic electron scattering (M-EELS), we observed sub-200 meV acoustic and optic phonons, which have previously been implicated in the superconducting pairing, and a valence plasmon from the free carriers. For a carrier density of 2.137×1020 cm-3, the plasmon blueshifts with decreasing temperature, while its width and dispersion deviate from RPA predictions. In this talk, I will discuss evidence for hybridization of these modes for different carrier densities.

*This work was supported by DOE grant DE-FG02-06ER46285. S.R. acknowledges support from NSF Graduate Research Fellowship DGE-1746047. P.A. acknowledges support from Gordon and Betty Moore Foundation EPiQS grant GBMF-4542.

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Presenters

  • Samantha Rubeck

    • University of Illinois at Urbana-Champaign

Authors

  • Samantha Rubeck

    • University of Illinois at Urbana-Champaign

  • Melinda S Rak

    • University of Illinois at Urbana-Champaign

  • Matteo Mitrano

    • University of Illinois at Urbana-Champaign

  • Ali Husain

    • University of Illinois at Urbana-Champaign

  • Jin Chen

    • University of Illinois at Urbana-Champaign

  • Alexander Edelman

    • University of Chicago
    • James Franck Institute and Department of Physics, University of Chicago
    • University of Chicago and Argonne National Laboratory

  • Peter B Littlewood

    • Argonne National Lab
    • James Franck Institute and Department of Physics, University of Chicago
    • Condensed Matter Theory, Argonne National Laboratory
    • University of Chicago and Argonne National Laboratory
    • Materials Science Division, Argonne National Laboratory

  • Peter Abbamonte

    • University of Illinois at Urbana-Champaign
    • University of Illinois,Urbana Champaign