Impact of magnetic frustration on the Mott transition within a slave-boson mean-field theory

Abstract

We investigate the paramagnetic-metal-to-antiferromagnetic-metal and antiferromagnetic-metal-to- antiferromagnetic-insulator transitions using a slave-boson mean-field theory. To this effect, we discuss the ground state of the half-filled Hubbard model as a function of t&#39;/t and correlation strength U, where t and t&#39; are the hopping amplitudes between nearest and next-nearest neighbors, respectively. The metal-insulator transition at a critical U_{MIT} is of second order for small levels of magnetic frustration, t&#39;/t<0.06, and of first order for large ones, t&#39;/t>0.06. The insulator is always antiferromagnetically ordered, while the metal exhibits a second-order transition from a paramagnetic to an antiferromagnetic state up to t&#39;/t=0.14, as U is increased. We also contrast these findings with what we obtain in Hartree-Fock approximation.