We discuss the particle size driven tunability of the coexistence of ferromagnetism and ferroelectricity in ${\mathrm{Pr}}_{0.67}{\mathrm{Ca}}_{0.33}{\mathrm{MnO}}_3$ (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 $P{2}_{1}nm$ 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.

• Received 28 August 2014
• Revised 22 October 2014

DOI:https://doi.org/10.1103/PhysRevB.90.245126