149Sm nuclear resonant scattering of SmB2C2

Abstract The quantum beat spectra due to magnetic ordering can be observed below the 51 K upper transition temperature of SmB 2 C 2 using the nuclear resonant forward scattering technique with the 149 Sm nuclei. The spectrum without dynamical or quantum beats can be observed at 60 K. This result indicates that the magnetic interaction continues to exist above 51 K. Examinations of the diffuse magnetic scattering of neutrons from HoB 2 C 2 show a similar continuation of the magnetic interaction above the Neel temperature. It appears that the spectrum at 60 K is caused by a distribution of the hyperfine magnetic field.