FLUX-DENSITY WAVE AND SUPERCONDUCTING INSTABILITY OF THE STAGGERED-FLUX PHASE

We study the stability of the staggered-flux phase in the t-J model away from half-filling using a systematic large-N slave-boson approach. Found below a critical doping concentration c=a(J/t)2, is a flux-density-wave instability with an incommensurability wave number 3/4. The instability towards a modulated-flux state is due to low-lying phase fluctuations of the valence bonds. When the doping parameter exceeds c, we find a fully gapped d-wave superconducting state due to residual quasiparticle interactions. © 1990 The American Physical Society.