CALCULATION OF SEMICONDUCTIVE PROPERTIES OF CACUO2-PLANAR PHASE WITH INTERPLANAR OXYGEN DEFECTS

The electronic properties of CaCuO2 in the tetragonal structure has been computed with the spin polarized, full potential pseudofunction energy band method. The bands are found to be metallic for the undistorted structure. An insulating antiferromagnetic ground state is obtained if some of the O atoms in the Cu-O plane are placed in the interplanar site between Cu-O planes so as to be co-layered with Ca. The magnetic moment on the Cu sites in this phase is 0.25-mu-B. This structure has bond lengths similar to that in the insulating orthorhombic phase of CaCuO2. In the case of the puckered Cu-O plane which was proposed on the basis of pulsed neutron experiments, semimetallic behavior is obtained. The microscopic origin of intrinsic flux pinning centers for the cuprates superconductivity is proposed based on our band structures for the O defect model. The density of states calculated for the orthorhombic phase agree well with photoemission spectra data for the CaCuO2 film.