Influence of the Jahn–Teller distortion on magnetic ordering in TbMn_1-xFe_xO₃

The Jahn-Teller distortion plays an important role in determining the exchange interaction in rare-earth manganites. In this work we study the influence of the Jahn-Teller distortion on the magnetic structures of TbMn_1-xFe_xO₃ (x=0, 0.02, 0.05, 0.10, and 0.20) single crystals in the basal MnO₂ plane. The decrease in the quadruple splitting with the increasing Fe doping indicates the reduction of the Jahn-Teller distortion, which makes the nearest neighboring (NN) FM interaction dominant over the next nearest neighbor (NNN) AFM interaction. This alteration is favorable for the development of A-type AFM ordering instead of the spiral magnetic ordering, which collapses when x≥0.05. The analysis of dielectric data indicates that the ferroelectricity is arising from the peculiar spiral magnetic ordering.