Effect of AFM and FM exchange interaction on magnetic anisotropy properties of single domain SmFeO3 at nanoscale

[Display omitted] •The magnetic behavior of the SFO depends on particle size and initial magnetic state.•Magneto crystalline anisotropy and unidirectional anisotropy of SFO depend on temperature.•Remnant magnetization, M−H behavior and Coercive field are highly dependent on particle size.•The particles remain in single domain state up to ~170 nm (critical size).•Coercive magnetic field and magnetization increases with particle size up to (~170 nm).•The single domain nanoparticle magnetic behavior is different to that of multi domain bulk.•At low temperature AFM and FM interaction leads to unidirectional anisotropy rotation of spins.•The compensation temperature is higher (~13 K) in nano-SFO compare to that of bulk (~4K).•Sm3+ spin unidirectional magnetic anisotropy is more effective in between ~13 K to ~65 K.•Fe3+ spin unidirectional anisotropy is effective beyond ~65 K.•Sm3+ spins can be rotated at ±50 Oe due to unidirectional anisotropy at low temperature. Multifunctional Samarium orthoferrites (SmFeO3) nano-particles have been studying extensively due to their applications in digital memory, ultrafast switching, temperature dependent spin valves and sensor applications. Magnetic properties of SFO were investigated by varying particle size, initial magnetic state of material and applied field under Zero Field Cooling (ZFC) and Field Cooling (FC) protocol. It was found that the remnant magnetization, M−H behavior and coercive field are extremely dependent on particle size. It was also found that the magnetic behavior of single domain SFO nanoparticle is completely different to that of multi domain bulk due to uniaxial magneto crystalline anisotropy. The magnetization vs temperature (M−T) behavior of nano-particle depends on unidirectional anisotropy along with uniaxial magneto-crystalline anisotropy of SFO. The Sm3+ spin ordering in nano-SFO compensates to that of Fe3+ spin ordering at higher temperature (~13 K) compare to that of bulk (~4K). The Sm3+ spin unidirectional magnetic anisotropy is more effective in between ~13 K to ~65 K and Fe3+ spin unidirectional anisotropy is effective at higher temperature beyond ~65 K. Magnetically poled nano-particles show completely different behavior to that of non-poled nano-SFO particles at low temperature. In nutshell, the manuscript shows why one can’t predict the magnetic behavior of the SFO without knowing its particle or grain size, initial magnetic state of the particle, procedure of measurement, the magnitud