PHOTOEMISSION-STUDY OF THE KONDO INSULATOR CE3BI4PT3

The electronic structure of the Kondo insulator Ce3Bi4Pt3 has been stu died by high-resolution photoelectron spectroscopy. Indications of the unusual electronic structure are observed: the 4f derived peak near t he Fermi level is located at a binding energy of 20 meV and is not cut -off by the Fermi edge as in conventional Kondo systems; for low photo n energies, where the 4f contribution is negligible and the conduction band states are probed, a loss of spectral intensity in the same ener gy range is observed. These observations are related to the opening of a gap at low temperature, confirming the picture that hybridisation b etween a localised 4f state and the conduction band is responsible for the insulating character of this material.