Tailoring the nature and strength of electron-phonon interactions in the SrTiO3(001) 2D electron liquid
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Surfaces and interfaces offer new possibilities for tailoring the many-body interactions that dominate the electrical and thermal properties of transition metal oxides1–4. Here, we use the prototypical two-dimensional electron liquid (2DEL) at the SrTiO3(001) surface5–7 to reveal a remarkably complex evolution of electron–phonon coupling with the tunable carrier density of this system. At low density, where superconductivity is found in the analogous 2DEL at the LaAlO3/SrTiO3 interface8–13, our angle-resolved photoemission data show replica bands separated by 100 meV from the main bands. This is a hallmark of a coherent polaronic liquid and implies long-range coupling to a single longitudinal optical phonon branch. In the overdoped regime the preferential coupling to this branch decreases and the 2DEL undergoes a crossover to a more conventional metallic state with weaker short-range electron–phonon interaction. These results place constraints on the theoretical description of superconductivity and allow a unified understanding of the transport properties in SrTiO3-based 2DELs.
Wang , Z , Walker , S M , Tamai , A , Wang , Y , Ristic , Z , Bruno , F Y , Torre , A D L , Riccò , S , Plumb , N C , Shi , M , Hlawenka , P , Sánchez-Barriga , J , Varykhalov , A , Kim , T K , Hoesch , M , King , P D C , Meevasana , W , Diebold , U , Mesot , J , Moritz , B , Devereaux , T P , Radovic , M & Baumberger , F 2016 , ' Tailoring the nature and strength of electron-phonon interactions in the SrTiO 3 (001) 2D electron liquid ' , Nature Materials , vol. 15 , no. 8 , pp. 835-839 . https://doi.org/10.1038/nmat4623
© 2016, the Author(s). This work is made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at www.nature.com / https://dx.doi.org/10.1038/nmat4623
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