Evidence for crystal-lattice modulation due to spatially restricted enhancement of mixing effect in the low-carrier system CeSb

In order to investigate the unusual magnetic properties of the low-carrier system CeSb, X-ray diffraction studies at low temperatures have been performed. Below the magnetic transition temperature of T_N = 17 K, several X-ray satellite peaks and their temperature variations were observed, which indicate that the modulated structures of a crystal lattice coexist with the long-period magnetic structures in CeSb. The observed wave numbers of the lattice modulations and the satellite-peak intensities are explained by the periodical arrangement of short and long distances between magnetic layers. The short interlayer distance is due to enhancement of p-f mixing effect which is spatially restricted within the ferromagnetic layers of Γ₈-like Ce ions appearing in the lattice of Γ₇ Ce ions. The interlayer distance due to Γ₈-like state is shorter by 0.1% than that between normal Γ₇ Ce layers.