J. Phys. I France
Volume 6, Numéro 12, December 1996
Page(s) 2291 - 2297
DOI: 10.1051/jp1:1996218
J. Phys. I France 6 (1996) 2291-2297

The EFG Analysis of La $\mathsf{_2}$CuO $\mathsf{_4}$ and YBa $\mathsf{_2}$Cu $\mathsf{_3}$O $\mathsf{_7}$ Based Superconductors

Ivan Kupcic1, Slaven Barisic1 and Eduard Tutis2

1  Department of Physics, POB 162, Faculty of Sciences, Zagreb, Croatia
2  Institute of Physics of the University, POB 304, Zagreb, Croatia

(Received 30 August 1996, accepted 3 September 1996)

It is shown that the 3d 3z2-r2 orbital of the in-plane copper and the 2p z apex oxygen orbital are absent at the Fermi level of La 2-xSr xCuO 4, at variance with proposals giving importance to copper-apex oxygen hybridization. At the in-plane oxygen site a sizable 2p z admixture is found at the Fermi level of YBa 2Cu 3O 7. The additional holes are shared among copper and oxygen sites in similar proportions. This is shown compatible with the large $U_{\rm d}$ Emery model provided that the difference between the p and d atomic energies is comparable to the first neighbor overlap energy.

© Les Editions de Physique 1996