Detailed Measurements of Characteristic Profiles of Magnetic Diffuse Scattering in ErB${}_2$C${}_2$

Detailed neutron diffraction measurements on a single crystalline ErB${}_2$C${}_2$ were performed. We observed magnetic diffuse scattering which consists of three components just above the transition temperatures, which is also observed in characteristic antiferroquadrupolar ordering compounds HoB${}_2$C${}_2$ and TbB${}_2$C${}_2$. The result of this experiments indicates that the antiferroquadrupolar interaction is not dominantly important as a origin of the magnetic diffuse scattering.