Spin excitons in heavy fermion semiconductors

The heavy fermion semiconductors such as Ce3Bi4Pt3, YbB12, and SmB6 may be modeled as indirect hybridization gap semiconductors. The magnitudes of the gaps are smaller than the gaps predicted by local density functional elect ronic structure calculations, suggesting strong renormalizations due to ele ctronic correlations. The inelastic neutron scattering spectra Im[chi (q, o mega)] are examined within the context of this model. Anomalously sharp and temperature dependent peaks are seen at energies within the indirect gap i n the inelastic neutron scattering experiments on SmB6 and YbB12. The in-ga p features are identified as a spin exciton excitations, which are induced by residual anti-ferromagnetic interactions between the renormalized quasi- particles. (C) 2001 Elsevier Science BY. All rights reserved.