Electronic structure of fluorinated YBa2Cu3O7

Abstract

With a view to interpreting recent experimental results bearing on the superconducting properties of fluorinated YBa2Cu3O7, we compare the band structures of pure and various forms of fluorinated YBa2Cu3O7. We find that the distinctive one-dimensional (1D) band features of pure YBa2Cu3O7 are preserved if F atoms are introduced at the O vacancy sites between adjacent 1D Cu-O ribbons, while these 1D features are disrupted if F atoms replace O atoms belonging to these ribbons. Assuming that the 1D band features of YBa2Cu3O7 reflect electronic and structural properties that are crucial to the occurrence of high values of Tc, we conclude that the incorporation of F atoms at O vacancy sites would have only a slight effect on Tc, while the substitution of F atoms for O atoms at Cu-O ribbon sites could drastically reduce Tc or destroy superconductivity altogether. Recent experimental reports for fluorinated YBa2Cu3O7 are discussed in the light of these theoretical results. © 1988 The American Physical Society.