Study of nodal gap in t-J model via renormalized mean field theory*

Angle-resolved photoemission (ARPES)[1] and scanning tunnelling microscopy (STM) [2] results show that Bi₂Sr_2−yLa_yCuO_6+δ exhibit a gap, instead of a node, near the nodal region for x < 0.1. A similar gap has also been found in lightly doped La_2−xSr_xCuO₄[3]. All these experiment results indicated that spin density wave (SDW) and nodal gap(NG) are closely related. However, why the NG close when the insulator-superconductor transition occurs remains unclear.

From the theoretical point of view, various degenerate intertwined order states have been investigated via renormalized mean field theory(RMFT) [4]. Among these states, we found that only the states accompanied by SDW open the nodal gap. Otherwise, there is either node or arc near nodal region. In this work, we will discuss the mechanism of the gap formation and show the gap evolution upon doping.

[1] Y. Peng, et al Nat. Commun.4, 2459 (2013).
[2]P. Cai, et al Nat. Phys. 12, 1047 (2016).
[3] E. Razzoli et al Phys. Rev. Lett. 110, 047004 (2013).
[4] W.-L. Tu and T.-K. Lee Sci. Rep. 6, 18675 (2016).