  The peculiar behavior of Kondo peak splitting under a magnetic field and bias
can be explained by calculating the nonequilibrium retarded Green's function
via the nonperturbative dynamical theory (NDT). In the NDT, the application of
a lead-dot-lead system reveals that new resonant tunneling levels are activated
near the Fermi level and the conventional Kondo peak at the Fermi level
diminishes when a bias is applied. Magnetic field causes asymmetry in the
spectral density and transforms the new resonant peak into a major peak whose
behavior explains all the features of the nonequilibrium Kondo phenomenon. We
also show the mechanism of coherent transport through the new resonant
tunneling level.
