Neutron Scattering Study on the Orbital Order of DyB2C2 in Magnetic Fields

Antiferroquadrupolar (AFQ) ordering in DyB 2 C 2 has been investigated by neutron scattering under applied magnetic fields. In the AFQ ordered phase, antiferromagnetic reflections indexed as 1,0,1/2, 1,0,1 and 1,0,3/2 appear upon applying magnetic fields, and develop with fields up to 2.5 T. These field induced AFM reflections are clear evidence of the AFQ order in DyB 2 C 2 . Experimental result shows that the induced magnetic dipolar moments are strongly suppressed by the AFQ order of the Dy quadrupolar moments. A possible model of this magnetic ordering is proposed.