Body-centered tetragonal La2CuO4 is shown to have its electronic structure and properties dominated by the layered in-plane Cu-3dO-2p interactions. A strong Fermi surface instability along  with q=2kF leads, via a soft-phonon mode, to the observed orthorhombic phase and accounts for its semiconducting properties. The addition of divalent metals, i.e., Ba, Sr, suppresses the instability and stabilizes the tetragonal phase where the same soft-phonon branch apparently contributes to a large electron-phonon interaction and a high Tc.
ASJC Scopus subject areas
- Physics and Astronomy(all)