Revealing the impact of ball milling as an intermediate stage in solid-state reaction synthesis of SmFeO3 particles

In this work, the impact of milling time on the structural, morphological, and magnetic properties is investigated in SmFeO₃ (SFO) powders obtained by solid state reaction. Specifically, the ball milling process is incorporated as an intermediate step during the synthesis and their magnetic properties vary when the samples are milled for 4 and 10 h. Based on X-ray diffraction, the resulting samples crystallized in Pbnm space group, with a slight decrease in crystallite size and cell volume with milling time. These results are also supported by confocal Raman microscopy with a slight shift towards lower wavenumbers. In this sense, magnetic characterization demonstrates a weak ferromagnetic contribution coexisting with the dominant antiferromagnetic order. Butterfly shaped hysteresis loops are observed in both samples for T > 200 K while a single shaped loop is achieved for T < 200 K. Zero field cooled, and field cooled magnetization curves shows a broad maximum centered at 140 K and bifurcation of the two curves because of the competing interaction between the Sm⁺³ and Fe³⁺ ions into the SFO crystal structure. Interestingly, exchange bias (EB) effect is found up to 200 K with a field cool of 20 kOe for both samples. The existence of Fe–Fe, Fe–Sm, and Sm–Sm interactions in a cluster glass state induced by ball milling processes might be the main cause of such EB effect.