Magnetic and quadrupole interaction studies at Cd-111 in GdMn2 and TbMn2

The temperature dependence of the electric quadrupole interaction and the m agnetic hyperfine field at Cd-111 probe sites in RMn2 (R = Gd, Tb) has been studied by TDPAC method. In the paramagnetic region the quadrupole interac tion frequency nu(Q) in both compounds varies linearly with temperature. Be low the Neel temperature, we find an abrupt decrease in the magnitude of nu (Q) which is consistent with an expansion of the unit cell. As an important feature, the data near T-N shows the coexistence of localized and itineran t magnetism of Mn atoms.