Antiferromagnetism and phase separation in the t-J model at low doping:: A variational study -: art. no. 104503

Using Gutzwiller-projected wave functions, I estimate the ground-state energy of the t-J model for several variational states relevant for high-temperature cuprate superconductors. The results indicate that both the superconducting state and the staggered-flux normal state (proposed for vortex cores) are unstable at low doping towards antiferromagnetism and towards phase separation. While phase separation in the underdoped superconducting state may be relevant for the stripe formation mechanism, the results for the normal state suggest that similar charge inhomogeneities may also appear in vortex cores up to relatively high doping values.