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 a new analytical approach. Contrary to expectations, the quasiparticle gap never vanishes at any field and no metal-insulator transition is found. We discuss generalizing our result to three dimensions and to the asymmetric Anderson lattice. Our result is consistent with recent experiments. 
Herve M. Carruzzo and Clare C. Yu (University of California, Irvine)