Synchrotron electron density probe of strongly correlated electron systems

Images of the electron density distribution for single crystals of CeB(6) and SmB(6) have been obtained from accurate synchrotron X-ray diffraction data. Electrons accumulate between neighbouring rare earth atoms in both compounds, along the [0 1 1] direction in CeB(6), and along the [1 1 1] and [0 1 1] directions in SmB(6). These results are consistent with homogeneous hybridization gap model and complement paramagnetic response studies for SmB(6) by inelastic neutron scattering which show excess spin density in the same regions. (C) 1999 Elsevier Science B.V. All rights reserved.