Absence of a magnetic-field-induced metal-insulator transition in Kondo insulators

We investigate whether or not Kondo insulators undergo a magnetic-field-induced metal-insulator transition in one dimension at half filling using both a density matrix formulation of the numerical renormalization group and bosonization. Contrary to expectations, the quasiparticle gap never vanishes at any field and no metal-insulator transition is found. We discuss generalizing our result to the asymmetric Anderson lattice.