Magnetic phase diagrams of Dy0.8Gd0.2B2C2

Gd substitution in DyB2C2, which undergoes an antiferroquadrupolar (AFQ) ordering at TQ = 24.7 K and an antiferromagnetic (AFM) one at TN 15.3 K, enhances the AFM interaction and weakens the AFQ interaction, and the transition sequence at 20% Gd is the reverse of that in DyB2C2. The AFQ transition occurs at TQ = 17.5 K, below the AFM one at TN = 19.0 K in Dy0.8Gd0.2B2C2. The present work provides some experimental results on the specific heat and magnetization of Dy0.8Gd0.2B2C2. The magnetic phase diagrams of Dy0.8Gd0.2B2C2 have some resemblance to those of HoB2C2 and Ce0.75La0.25B6. There is an anomalous magnetic phase (named phase IV) that is adjacent to the AFQ phase in each compound