MAGNETIC-PROPERTIES OF THE 2D T-T''-HUBBARD MODEL

The two-dimensional(2D) t-t'-Hubbard model is studied within the slave -boson (SE) theory. At half-filling, a paramagnetic to antiferromagnet ic phase transition of first order at a finite critical interaction st rength U-c(t'/t) is found. The dependences on U/t and t'/t of the subl attice magnetization and of the local magnetic moment are calculated. Our results reasonably agree with recent (Projector) Quantum Monte Car lo data. The SE ground-state phase diagram reveals a t'-induced electr on-hole asymmetry, and, depending on the ratio t'/t, the antiferromagn etic or ferromagnetic phases are stable down to Ci = 0 at a critical h ole doping.