Intrinsic phase fluctuation and superfluid density in doped Mott insulators

The doping dependence of the superfluid density $\rho_{\text{s}}$ exhibits distinct behaviors in the underdoping and overdoping regimes of the cuprate, while the superconducting (SC) transition temperature $T_c$ generally scales with $\rho_{\text{s}}$. In this paper, we present a unified understanding of the superconducting transition temperature $T_c$ and $\rho_{\text{s}}$ across the entire doping range by incorporating the underlying mutual Chern-Simons gauge structure that couples the spin and charge degrees of freedom in the doped Mott insulator. Within this framework, the SC phase fluctuations are deeply intertwined with the spin dynamics, such that thermally excited neutral spins determine $T_c$, while quantum spin excitations effectively reduce the superfluid density at zero temperature. As a result, a Uemura-like scaling of $T_c$ vs. $\rho_{\text{s}}$ in the underdoped regime naturally emerges, while the suppression of both $T_c$ and $\rho_{\text{s}}$ at overdoping is attributed to a drastic reduction of antiferromagnetic spin correlations.