ON THE ROLE OF APICAL OXYGENS IN HIGH-TC CU-OXIDES

The role of apical oxygens in high-Tc Cu-oxides has been analyzed based on the effective Hamiltonian derived previously by the present authors. It turns out that these oxygens modulate notably the oxygen p-hole band structure, which leads to the enhancement of the long-range hopping integrals of the Zhang-Rice singlet. This effect is further enhanced if the distance between apical O and in-plane Cu is reduced. This finding may relate to the remarkable experimental result by Murayama et al. of the strong pressure dependence of Tc in the T* structure and its complete absence in the T' structure. © 1990, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.