Charge Carrier Mass in High Tc Superconductors

The theory of polarons has experienced a surge of activity in the last years partly due to the possible role of polaronic quasiparticles in high Tc superconductors. This numerical study of the Holstein model shows that the polaronic effective masses become essentially dimension independent and of order ≃10–50 times the electron mass at sufficiently strong intermolecular coupling forces. Such values (which are much lower than those obtained by traditional small polaron theory) would erase one the serious objections against a (bi)polaronic picture for high Tc superconductors.