Electronic structure of pure and doped orthorhombic La₂CuO₄

Abstract

The electronic structure of orthorhombic La2CuO4 has been investigated by first principles pseudofunction band calculations and group theoretical analysis. We find that pure as well as doped compounds remain metallic at all finite temperatures as a conseqence of the Cmca (D182h) space group symmetry. The experimentally observed rapid rise in resistivity below 30°K suggests a structural transition to a lower symmetry space group that could be driven electronically or magnetically. One possible candidate is monoclinic C2/m (C32h) which is a subgroup of Cmca and can be obtained by distorting the CuO bonds or rotating the CuO6 octahedra. Implications for superconductivity are discussed. © 1987.