Observation of enhanced magnetic transition in Pbnm SmFeO₃

Rare-earth orthoferrite RFeO₃ materials have recently attracted great attention for their intriguing technological potential. Among these materials, SmFeO₃ holds great promise, not only for its excellent physical properties (fast magnetic switching, spin reorientation, and magnetization reversal), but also for its potential ferroelectric properties, which have been recently under debate. Here, we focus our attention on the T-dependent Zero Field Cooled and Field Cooled magnetization properties of micrometer scale crystals of SmFeO₃ obtained by annealing methods. We report the observation of an enhanced magnetic transition at a temperature of approximately 139 K. From literature bulk susceptibility measurements, it has been suggested that below the temperature of about 140 K, Sm³⁺ moments begin to order antiparallel to the Fe-moments due to antiferromagnetic f-d exchange interactions. We attribute the observed transition to compensation effects induced by the appearance of long range ordering in Sm³⁺ spins. The magnetic-nature of the observed transition is confirmed by additional temperature dependent XRD analysis, which did not show structural changes in the samples in the same temperature range (from 298 K to 100 K). Due to residual small fractions of ferromagnetic α-Fe from the sample-growth, possible interactions between the magnetic moment of α-Fe and the SmFeO₃ crystals at the compensation temperature cannot be excluded and could be at the origin of the enhanced magnetic signal reported in this work.