Insulator-to-metal transition in Kondo insulators under a strong magnetic field

Magnetization curve and changes of the single-particle excitation spectra by magnetic field are calculated for the periodic Anderson model at half-filling in infinite spatial dimension by using the exact diagonalization method. It is found that the field-induced insulator-to-metal transition occurs at a critical field ${\mathit{H}}_{\mathit{c}}$, which is of the order of the single-ion Kondo temperature. The transition is of first order, but could be of second order in the infinite system size limit. These results are compared with the experiments on the Kondo insulator ${\mathrm{YbB}}_{12}$. © 1996 The American Physical Society.