Synthesis of single-crystalline BiFeO3 nanoparticles and their magnetic properties

Single-crystalline multiferroic BiFeO3 (BFO) nanoparticles with R3c space group have been synthesized via sol-gel process. The BFO nanoparticles exhibit weak ferromagnetism at low temperatures and antiferromagnetic behavior at room temperature. An unexpected abrupt increase of the magnetization at approximate to 10K was found in the ZFC curve, which could be ascribed to a competition between the ferromagnetization (particle sizes below 62nm) and anti-ferromagnetization (particle sizes over 62nm). In addition, M-H loops reveal an exchange bias effect in the BFO nanoparticles, which reaches a maximum at 10K.