Nonadiabatic coupling of the dynamical structure to the superconductivity in YSr2Cu2.75Mo0.25O7.54 and Sr2CuO3.3

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Proceedings of the National Academy of Sciences of the United States of America, Volume 117, issue 52
A crucial issue in cuprates is the extent and mechanism of the coupling of the lattice to the electrons and the superconductivity. Here we report Cu K edge extended X-ray absorption fine structure measurements elucidating the internal quantum tunneling polaron (iqtp) component of the dynamical structure in two heavily overdoped superconducting cuprate compounds, tetragonal YSr2Cu2.75Mo0.25O7.54 with superconducting critical temperature, Tc = 84 K and hole density p = 0.3 to 0.5 per planar Cu, and the tetragonal phase of Sr2CuO3.3 with Tc = 95 K and p = 0.6. In YSr2Cu2.75Mo0.25O7.54 changes in the Cu-apical O two-site distribution reflect a sequential renormalization of the double-well potential of this site beginning at Tc, with the energy difference between the two minima increasing by ∼6 meV between Tc and 52 K. Sr2CuO3.3 undergoes a radically larger transformation at Tc, >1-Å displacements of the apical O atoms. The principal feature of the dynamical structure underlying these transformations is the strongly anharmonic oscillation of the apical O atoms in a double-well potential that results in the observation of two distinct O sites whose Cu-O distances indicate different bonding modes and valence-charge distributions. The coupling of the superconductivity to the iqtp that originates in this nonadiabatic coupling between the electrons and lattice demonstrates an important role for the dynamical structure whereby pairing occurs even in a system where displacements of the atoms that are part of the transition are sufficiently large to alter the Fermi surface. The synchronization and dynamic coherence of the iqtps resulting from the strong interactions within a crystal would be expected to influence this process.
Funding Information: ACKNOWLEDGMENTS. We acknowledge the financial support from the Slovenian Research Agency (research core funding no. P1-0040). Work at Washington State University is partially supported by the US National Science Foundation Division of Materials Research Early Concept Grants for Exploratory Research Grant 1928874. Work at Institute of Physics, Chinese Academy of Sciences was supported by the Ministry of Science and Technology and National Natural Science Foundation of China. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract DE-AC02-76SF00515. Work at Stanford and SLAC is supported by the Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, under Department of Energy, Office of Basic Energy Sciences Contract DEAC02-76SF00515. We thank A. R. Bishop, I. Bozovic, A. Bussmann-Holder, S. A. Kivelson, D. Mihailovic, and C. Varma for helpful discussions and presubmssion reviews of this manuscript. Publisher Copyright: © 2020 National Academy of Sciences. All rights reserved. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.
cuprates, dynamical structure, superconductivity, tunneling polarons, X-ray absorption fine structure
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Conradson , S D , Geballe , T H , Jin , C Q , Cao , L P , Gauzzi , A , Karppinen , M , Baldinozzi , G , Li , W M , Gilioli , E , Jiang , J M , Latimer , M , Mueller , O & Nasretdinova , V 2020 , ' Nonadiabatic coupling of the dynamical structure to the superconductivity in YSr 2 Cu 2.75 Mo 0.25 O 7.54 and Sr 2 CuO 3.3 ' , Proceedings of the National Academy of Sciences of the United States of America , vol. 117 , no. 52 , pp. 33099-33106 .