By the first-principles variational calculations we show that, with the increase of Sr concentration, the ground state of CuO6 octahedron in La2-xSrxCuO4 changes from 1A1g to 3B1g near the observed onset concentration of superconductivity while the ground state of the CuO4 cluster in Nd2-xCexCuO4 is always 3B1g in the presence of dopant electrons. Based on this result, two kinds of phase diagrams are predicted for hole- and electron-doped superconductors. These results support the spin polaron mechanism proposed by Kamimura et al.
ASJC Scopus subject areas
- Physics and Astronomy(all)