Coherence and metamagnetism in the two-dimensional Kondo lattice model

We report the results of dynamical mean-field calculations for the metallic Kondo lattice model subject to an applied magnetic field. High-quality spectral functions reveal that the picture of rigid, hybridized bands, which are Zeeman shifted in proportion to the field strength, is qualitatively correct. We find evidence of a zero-temperature magnetization plateau whose onset coincides with the chemical potential entering the spin up hybridization gap. The plateau appears at the field scale predicted by a (static) large-N mean-field theory and has a magnetization value consistent with that of x = 1 - n(c) spin-polarized heavy holes, where n(c) < 1 is the conduction band filling of the noninteracting system. We argue that the emergence of the plateau at a low temperature marks the onset of quasiparticle coherence.