The t-J model is a paradigmatic model for the study of strongly correlated electron systems. In particular, it has been argued that it is an appropriate model to describe the cuprate high-T c superconductors. It turns out that a comprehensive understanding of the gamut of physics encoded by the t-J model is still an open problem. In recent years some remarkable experiments on the cuprates, for example, discovery of nodeless superconductivity in underdoped samples (PNAS 109, 18332 (2012)), discovery of s-wave like gap in the pseudogap phase (Phys. Rev. Lett. 111, 107001 (2013)), and observation of polar Kerr effect (PKE) (Phys. Rev. Lett. 112, 047003 (2014)), have thrown up new challenges for this model. Here, we present results demonstrating that, within the slave-particle formulation of the t-J model, the d-wave superconductor is unstable at low doping to its own anti-symmetric phase mode fluctuations when the effect of fluctuations is treated selfconsistently. We then show that this instability gives way to a time reversal symmetry broken d + is-SC in the underdoped region which has superfluid stiffness consistent with Uemura relation, even with a large pair amplitude. We show that our results are consistent with existing experiments on cuprates and suggest that Josephson (SQUID interferometry) experiments can clearly distinguish the d+is-SC from a host of other possibilities alluded to be contributing to the physics of underdoped cuprates. We also comment on other theoretical studies vis-a-vis ours.The rich phase diagram of the copper oxide high-T c superconductors has been a major source of inspiration for several fields of inquiry in both experimental and theoretical condensed matter physics 1 . One of the important theoretical offshoots has been the extensive study of strongly correlated model systems like the t-J model 2-4 . While this model has been quite successful in explaining several features of the cuprate phase diagram 5-7 , a comprehensive understanding of the low temperature phase in the underdoped region is yet to be achieved 8,9 . Recent experiments like the observation of nodeless superconductivity in the underdoped cuprates 10,11 , and, clear signatures of breaking of time reversal symmetry 12,13 raise new challenges. A natural question one would like to ask is how much of this new physics is within the scope of the t-J model? The difficulty in addressing this question is two fold: 1) strong electron correlations, and, 2) increased importance of long-wavelength fluctuations because of low dimensionality. Numerical techniques like the Variational Monte Carlo (VMC) using projected mean field like wavefunctions 14,15 or Projected Entangled Pair States (PEPS) 9 do a good job of accounting for strong correlations, but miss out on the long-wavelength fluctuations because of finite size limitations. The cluster DMFT 16 studies on the related Hubbard model have similar issues.The slave-particle formulation of the t-J model 17,18 has an unique advantage in this respect. At the mean field level it agr...
The enigmatic cuprate superconductors have attracted resurgent interest with several recent reports and discussions of competing orders in the underdoped side. Motivated by this, here we address the natural question of fragility of the d-wave superconducting state in underdoped cuprates. Using a combination of theoretical approaches we study t-J like models, and discover an -as yet unexplored -instability that is brought about by an "internal" (anti-symmetric mode) fluctuation of the d-wave state. This new theoretical result is in good agreement with recent STM and ARPES studies of cuprates. We also suggest experimental directions to uncover this physics.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.