Superfluid stiffness in cuprates: Effect of Mott transition and phase competition

Superfluid stiffness ρs is a defining characteristic of the superconducting state, allowing phase coherence and supercurrent. It is accessible experimentally through the penetration depth. Coexistence of d-wave superconductivity with other phases in underdoped cuprates, such as antiferromagnetism or charge-density waves, may drastically alter ρs. To shed light on this physics, the zeroerature value of ρs=ρzz along the c axis was computed for different values of Hubbard interaction U and different sets of tight-binding parameters describing the higherature superconductors YBCO and NCCO. We used cellular dynamical mean-field theory for the one-band Hubbard model with exact diagonalization as impurity solver and state-of-the-art bath parametrization. We conclude that Mott physics plays a dominant role in determining the superfluid stiffness on the hole-doped side of the phase diagram. On the electron-doped side, antiferromagnetism wins over superconductivity near half-filling. But, upon approaching optimal electron-doping, homogeneous coexistence between superconductivity and antiferromagnetism causes the superfluid stiffness to drop sharply. Hence, on the electron-doped side, it is competition between antiferromagnetism and d-wave superconductivity that plays a dominant role in determining the value of ρzz near half-filling. At large overdoping, ρzz behaves in a more BCS-type manner in both the electron- and hole-doped cases. We comment on some qualitative implications of these results for the superconducting transition temperature.