engleski

The EFG analysis of La2CuO4 and YBa2Cu3O7 based superconductors

It is shown that the $3d_{;3z^2 - r^2};$ orbital of the in-plane copper and the $2p_z$ apex oxygen orbital are absent at the Fermi level of La$_{;2-x};$Sr$_x$CuO$_4$, 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$_2$Cu$_3$O$_7$. The additional holes are shared among copper and oxygen sites in similar proportions. This is shown compatible with the large $U_d$ Emery model provided that the difference between the $p$ and $d$ atomic energies is comparable to the first neighbor overlap energy.

nuclear magnetic resonance and relaxation; Y-based cuprates

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