Electron mechanism for the tilting transition in La2-x SrxCuO4

Abstract

It is shown that the tilting deformation is couplet to the electrons through the tilting induced variation of the Umklapp matrix elements. The latter are important only for small concentrations of Sr if the electron-electron interaction, (which are assumed to be repulsive), are reasonably small. The leading term in the resulting deformation energy is quadratic in the tilting deformation and leads to the critical devease of the tilting mode frequency when the temperature is lowered. The resistivity, although enhanced by Umklapps, is continuous through the tilting transition. The model bears some ressemblence to that developed previously for 4 k f deformations in organic superconductors. Some consequences of the model for the high T c superconductivity are briefly discussed Description de la transition a la phase ondulee en termes d'interactions electroniques (couplage de la deformation aux electrons par l'intermediaire de la variation des elements de matrice Umklapp). Consequences pour la supraconductivite a T c elevee