Novel Magnetic Behavior Affected by Multipolar Interactions in the Tetragonal RB2C2Compounds (R = Tb, Dy and Ho)

Abstract

The present report reviews the experimental works on the tetragonal RB 2 C 2 compounds performed based on our interest in novel magnetic properties strongly affected by multipolar interactions by means of magnetization, specific heat, neutron diffraction and 161 Dy Mossbauer experiments. Our finding of an antiferroquadrupolar (AFQ) ordering below T Q =24.7 K in DyB 2 C 2 triggered the successive findings as follows. HoB 2 C 2 , unexpectedly, shows an AFQ transition at T Q =4.5 K below an antiferromagnetic transition (AFM) transition at T N =5.9 K. An AFM compound TbB 2 C 2 with T N =22.0 K shows an anomalous increase of susceptibility below T N , and the magnetic structure is a peculiar one among the RB 2 C 2 compounds. Furthermore, it is confirmed by neutron diffraction of the single crystal that an AFQ ordered phase is induced by magnetic fields.