  In transition metal oxides, quantum confinement arising from a large surface
to volume ratio often gives rise to novel physico-chemical properties at
nanoscale. Their size dependent properties have potential applications in
diverse areas, including therapeutics, imaging, electronic devices,
communication systems, sensors, and catalysis. We have analyzed structural,
magnetic, dielectric, and thermal properties of weakly ferromagnetic SmFeO3
nanoparticles of sizes about 55 nm and 500 nm. The nano-size particles exhibit
several distinct features that are neither observed in their larger-size
variants nor reported previously for the single crystals. In particular, for
the 55 nm particle, we observe six-fold enhancement of compensation
temperature, an unusual rise in susceptibility in the temperature range 550 to
630 K due to spin pinning, and coupled antiferromagnetic-ferroelectric
transition, directly observed in the dielectric constant.
