Evidence of antiferroquadrupolar ordering of DyB₂C₂

Abstract

The antiferroquadrupolar ordering in DyB2C2 has been investigated using the x-ray resonant scattering technique. The dependence of the intensities of two superlattice peaks on temperature, azimuthal angle, and energy of the incident x-rays was measured. The results show that the antiferroquadrupole ordering, which accompanies a structural phase transition, exists below TQ = 25 K. A structural model for the antiferroquadrupole ordering, for which the propagation vectors are (0,0,1/2) and (0,1,1/2), is presented.