Band-renormalization effects on antiferromagnetism and d-wave superconductivity in two-dimensional t-J model

Recent studies reported that antiferromagnetic (AF) states become stable and d-wave superconducting (d-SC) states are almost excluded in underdoped strongly correlated Hubbard models in two dimensions. In a viewpoint of many-body variational theory, this result stems from a band-renormalization effect (BRE) in AF states. Here, using a variational Monte Carlo method, BRE on AF and d-SC states are studied in the t-t'-J model, in which d-SC (AF) states have been considered to be more stable (fragile) than in the Hubbard model. Many features are qualitatively similar to the Hubbard model including effectiveness of BRE and the existence of a Lifshitz transition in AF states. However, a d-SC state becomes more stable than an AF state widely in the underdoped regime for J/t=0.3, in contrast to the Hubbard model.