Apical dynamics modulated in-plane properties in cuprates.

Since the discovery of high-temperature superconductivity in hole-doped La₂CuO₄, the mechanism of cuprate superconductors has been one of the most important problems in condensed matter physics. In this talk, we show, using ab initio simulations, a new trend that the bonding strength between the apical cation (e.g. La, Hg, Bi Tl) and apical anion (O, Cl) is positively correlated with experimental T_c,max across the hole-doped cuprates. The “apical structure unit” formed by the apical anion and the apical cation, the in-plane Cu and its nearest oxygen neighbors is a fundamental building block that can couple dynamically to control the superconductive properties. We present the underlying fundamental phenomena of coupled apical charge flux and the phonon/lattice dynamics of apical oxygen. Cooperative apical charge fluxes modulate the in-plane transport property by dynamically change both hopping integral and charge transfer energy. We believe our understanding here can shed light on the understanding of the complicated phenomena in cuprates, especially how the transport properties are controlled by the coupled electronic and ionic dynamic oscillations.
Reference
S. Kim, X. Chen, W. Fitzhugh, and X. Li, Physical Review Letters, 121, 157001 (2018)