Latent Room-Temperature T_c in Cuprate Superconductors

Abstract

The ancient phrase, "All roads lead to Rome" applies to Chemistry and Physics. Both are highly evolved sciences, with their own history, traditions, language, and approaches to problems. Despite all these differences, these two roads generally lead to the same place. For high temperature cuprate superconductors however, the Chemistry and Physics roads do not meet or even come close to each other. In this paper, we analyze the physics and chemistry approaches to the doped electronic structure of cuprates and find the chemistry doped hole (out-of-the-CuO_2-planes) leads to explanations of a vast array of normal state cuprate phenomenology using simple counting arguments. The chemistry picture suggests that phonons are responsible for superconductivity in cuprates. We identify the important phonon modes, and show that the observed T_c∼100 K, the T_c-dome as a function of hole doping, the change in T_c as a function of the number of CuO_2 layers per unit cell, the lack of an isotope effect at optimal T_c doping, and the D-wave symmetry of the superconducting Cooper pair wavefunction are all explained by the chemistry picture. Finally, we show that "crowding" the dopants in cuprates leads to a pair wavefunction with S-wave symmetry and T_c≈280−390 K. Hence, we believe there is enormous "latent" T_c remaining in the cuprate class of superconductors.

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