Magnetic bound states in SmB6

The heavy fermion semiconductors such as Ce3Bi4Pt3, YbB12, and SmB6 may be modeled as indirect hybridization gap semiconductor. The magnitudes of the gap are smaller than the gaps predicted by local density functional electronic structure calculations, suggesting strong renormalizations due to electronic correlations. The inelastic neutron scattering spectra Im[χ(q,ω)] are examined within the context of this model. Anomalously sharp and temperature dependent peaks are seen at energies within the indirect gap in the inelastic neutron scattering experiments on SmB6 and YbB12. The in-gap features are identified as excitations of magnetic bound states, which are induced by residual anti-ferromagnetic interactions between the renormalized quasi-particles.