Magnetic structure modified by the quadrupolar interaction in DyB2C2

Neutron powder diffraction experiments were performed on the tetragonal DyB 2C2 compound in order to determine its magnetic structure. DyB2C2 undergoes two phase transitions: one is a quadrupolar ordering at T-Q = 24.7 K, and the other a magnetic ordering at T-C = 15.3 K. The magnetic structure below T-C is complicated, which is essentially an antiferromagnetic one with sma ll ferromagnetic components. This complicated magnetic structure is due to the coexistence and competition of antiferromagnetic and antiferroquadrupol ar interactions. (C) 1999 Published by Elsevier Science Ltd, All rights res erved.