Neutron diffraction study of magnetic structure in DyCu under magnetic field

摘要

We have investigated the magnetic structure of the first field-induced phase (FM-I_(111)) of DyCu under a magnetic field applied in the [1 1 1] direction at 2.8 K, which is below T_N=63.0 K, by means of neutron diffraction experiments using a single crystal. With the magnetic transition fromthe antiferromagnetic (AFM) phase to the FM-I_(111) phase at 8.0 T, the intensity of (1/2)(1/2)-bar O reflection decreases sharply. The intensity in the FM-I_(111) phase is about three-fourths of the intensity in the AFM phase. This experimental result suggests that the magnetic structure model proposed by Amara et al. [J. Phys. Condens. Matter 9, 7441 (1997)] is appropriate for the FM-I_(111) phase. Considering the present results and the previous results reported by Amara et al., we have quantitatively evaluated the exchange and quadrupolar interaction energies based on a mean-field approximation. These interaction energies in the AFM and FM-I_(111) phases are found to be comparable.