Magnetic properties of NdMn1−xFexO3+δ (0≤x≤0.3) system.

• Fe substitution into NdMnO3 compound decreases TN by 10 K for 10% of Fe.
• In this compound: Nd and Mn ions both order magnetically.
• “Butterfly-type” hysteresis loops in the ordered state.

We have studied the effect of Fe for Mn substitution on magnetic properties of NdMn1−xFexO3+δ compounds. Our heat capacity, AC susceptibility and magnetization measurements revealed that the transition from paramagnetic to magnetically ordered state of the Mn sublattice decreases linearly from TN=74.9 K to TN=49 K with doping up to x=0.25. The ordering temperature T1 of Nd sublattice varies in a non-monotonous way in the temperature range 11–16 K. For x=0.3, the ordering of the Mn/Fe sublattice is residual, while the magnetism in Nd sublattice seems to be intact. The broad maximum in heat capacity C(T) at about 10 K was ascribed by 2-level Schottky contribution (Δ=21(1) K) for x=0, but this description failed for Fe-doped samples. An upturn of C(T) at temperatures below 0.5 K was observed on NdMnO3 and can be accounted to nuclear contribution. A more detailed study of AC susceptibility performed on samples with x=0.1 and 0.2 revealed a shift of both peaks to higher temperature with increasing frequency. The compensation temperature and a large negative field-cooled magnetization was observed for concentrations x=0.2 and x=0.25.