Bond polarons and high-Tc superconductivity in single layer   La_(2-x)Sr_xCuO_4: normal state currents and pairing
  We use the term "bond polaron" for a phonon coupled entity which makes the link between neighboring conductive CuO_2 layers in high-Tc superconductive materials. The link is essential for the superconductivity which requires a long range phase coherence in addition to pairing of carriers. The linkage features studied point to a process which is less dependent on the doped hole density implanted as x in the solid solution. The analysis applies to single layered materials mostly but may help understand multilayer ones as well. 
Mladen Georgiev
physics.gen-ph