  Using the results of x-ray and neutron diffraction experiments, we show that
the ferroelectric polarization, in ~22 nm particles of BiFeO3, exhibits a jump
by ~30% around the magnetic transition point T_N (~635 K) and a suppression by
~7% under 5T magnetic field at room temperature (<<T_N). These results confirm
presence of strong multiferroic coupling even in nanoscale BiFeO3 and thus
could prove to be quite useful for applications based on nanosized devices of
BiFeO3.
