Correlation between Cu deficiencies and changes in the structural and electrical properties of Y-Ba-Cu-O films

The experimental results obtained in our previous work included those of the copper composition dependences of structural, dc electrical and microwave properties. From these results, we proposed the inhomogeneous superconductor model that explains the correlation between the dc electrical and the microwave properties. Our recent measurements of the Hall coefficients suggested an additional model to explain the correlation between the structural and the electrical changes. Namely, copper deficiencies are compensated by the oxygen loss due to charge invariance. This oxygen reduction transforms locally the lattice from an orthorhombic phase into tetragonal-like phase. The resultant lattice disorder causes the low mobility and high resistivity.