  We discuss the particle size driven tunability of the coexistence of
ferromagnetism and ferroelectricity in Pr0.67Ca0.33MnO3(PCMO) with the help of
x ray diffraction, magnetization, impedance spectroscopy, and remanent
polarization measurements. The remanent polarization measurements using the
positive up negative down method clearly prove the existence of
ferroelectricity in PCMO with phase separation between Zener polaron(ZP)
ordered P21nm and disordered Pbnm structures. We also find that the
ferroelectric response is enhanced in nanocrystalline samples so long as ZP
ordering is not destroyed while the long-range antiferromagnetic ordering at
low temperature in bulk system is replaced by ferromagnetic correlations in
nanoparticles. The conclusion that by reducing the crystallite size it might be
possible to make ferromagnetism and ferroelectricity coexist near room
temperature should be generally applicable to all ZP ordered manganites.
