On the dynamic distinguishability of nodal quasi-particles in overdoped cuprates

La1.67Sr0.33CuO4 is not a superconductor and its resistivity follows a purely T-2 temperature dependence at very low temperatures. La1.71Sr0.29CuO4, on the other hand, has a superconducting ground state together with a T-Linear term in its resistivity. The concomitant emergence of these two features below a critical doping is mystifying. Here, I notice that the electron-electron collision rate in the Fermi liquid above the doping threshold is unusually large. The scattering time of nodal quasi-particles expressed in a dimensionless parameter zeta is very close to what has been found in liquid He-3 at its melting pressure. In the latter case, fermionic particles become dynamically distinguishable by excess of interaction. Ceasing to be dynamically indistinguishable, nodal electrons will be excluded from the Fermi sea. Such non-degenerate carriers will then scatter the degenerate ones within a phase space growing linearly with temperature.

Automated summary

La1.67Sr0.33CuO4 is not a superconductor with a T-2 temperature dependence, while La1.71Sr0.29CuO4 exhibits superconductivity with a T-Linear term in its resistivity. The unusually large electron-electron collision rate above a critical doping may play a role in the emergence of these two distinct features.