2-DIMENSIONAL T-J MODEL AT LOW ELECTRON-DENSITY

The phase diagram of the two-dimensional t-J model is determined accur ately at low electron density by a combination of analytic and numeric al techniques. The ground state exhibits three phases in the limit of aero-electron density: an unpaired state at small J/t, a gas of s-wave pairs for 2 < J/t less than or similar to 3.4367, and a phase-separat ed state at larger interaction strengths. Bound states of larger clust ers are never realised, and the instabilities present at small densiti es are discussed.