ELASTIC SOFTENING IN SUPERCONDUCTING LA2-XSRXCUO4

A theoretical model for the elastic softening observed in La2-xSrxCuO4 is presented. It is shown that the electronic redistribution mechanis ms between the strain-split itinerant p bands and also between the str ain-shifted energy pockets can satisfactorily account for the elastic softening of c66 and ((c11 - c12)/2. The result suggests that the Ferm i level shifts from the M point to the GAMMA point as a consequence of the tetragonal-to-orthorhombic structural transition. Implications of the present result on the superconducting mechanism are discussed.