Direct evidence for the magnetic ordering of Nd ions in NdMn$_2$Si$_2$   and NdMn$_2$Ge$_2$ by high resolution inelastic neutron scattering
  We have investigated the low energy nuclear spin excitations in NdMn$_2$Si$_2$ and NdMn$_2$Ge$_2$ by high resolution inelastic neutron scattering. Previous neutron diffraction investigations gave ambiguous results about Nd magnetic ordering at low temperatures. The present element-specific technique gave direct evidence for the magnetic ordering of Nd ions. We found considerable difference in the process of the Nd magnetic ordering at low temperature in NdMn$_2$Si$_2$ and NdMn$_2$Ge$_2$. Our results are consistent with those of magnetization and recent neutron diffraction measurements. 
T. Chatterji, J. Combet, B. Frick, and A. Szyula
cond-mat.str-el cond-mat.mtrl-sci