Energetics of Domain Walls in the 2D t-J model

Using the density matrix renormalization group, we calculate the energy of a domain wall in the 2D t-J model as a function of the linear hole density \rho_\ell, as well as the interaction energy between walls, for J/t=0.35. Based on these results, we conclude that the ground state always has domain walls for dopings 0 < x < 0.3. For x < 0.125, the system has (1,0) domain walls with \rho_\ell ~ 0.5, while for 0.125 < x < 0.17, the system has a possibly phase-separated mixture of walls with \rho_\ell ~ 0.5 and \rho_\ell =1. For x > 0.17, there are only walls with \rho_\ell =1. For \rho_\ell = 1, diagonal (1,1) domain walls have very nearly the same energy as (1,0) domain walls.