Based on density-functional calculations,we have studied possible ferroelectric switching path in monodomain single crystal of rhombohedral BiFeO_(3),a prototypical multiferroic compound.By carefully studying the behaviors of FeO_(3)corner-sharing double-tetrahedrons,we find abrupt changes in total energy and oxygen atomic positions,and therefore polarizations,occur in the ferroelectric switching path of rhombohedral BiFeO_(3).Detailed analyses suggest that such behavior might be caused by the frustrated magnetic ordering in the paraelectric phase of rhombohedral BiFeO_(3),where three O atoms and the Bi atom are in the same plane perpendicular to the polar-ization direction.This is supported by the fact that the ferroelectric switching for paramagnetic BiFeO_(3)is smooth and has a much lower energy barrier than that of an tiferromagnetic BiFeO_(3).
