Many strongly correlated systems, such as the cuprate superconductors, have the interesting physics of low dimensionality and hence enhanced fluctuation effects. We perform an analysis of the $t\text{−}J$ model in the slave boson formulation which accounts for strong correlations, focusing on fluctuation effects that have hitherto not received the attention they deserve. We find several interesting results including the instability of the $d$-wave superconducting state to internal phase fluctuations giving way to a time reversal broken $d+i{s}^{*}$ superconductor at low doping. This offers an explanation for some recent experimental findings in the cuprate superconductors, including the observation of nodeless superconductivity at low doping. We also suggest further experiments that can validate our claims. On a broader perspective, this work points to the importance of considering fluctuation effects in other two-dimensional strongly correlated systems opening up a plethora of possibilities.

• Received 28 February 2019
• Revised 9 February 2020
• Accepted 16 March 2020

DOI:https://doi.org/10.1103/PhysRevLett.124.147002