properties of Y-and Ni-doped TbMnO 3 are investigated. Both for Y and Ni doping, the Néel
temperature (TN) decreases. Y doping reduces effectively both the J Tb–Tb and J Mn–Mn
exchange interactions, whereas Ni doping on the Mn site decreases only the J Mn–Mn
exchange interaction. The reduction in TN in the Ni-doped sample cannot be explained with
simple exchange integral. It might be the case that Ni 2+ doping changes the polarization …