Direct experimental evidence of multiferroicity in a nanocrystalline Zener polaron ordered manganite

Abstract

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 (XRD), magnetization, impedance spectroscopy and remanent polarization measurements. The remanent polarization measurements using 'Positive Up Negative Down' (PUND) 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. [Published: Phys. Rev. B 90, 245126 (2014)]

Antiferromagnetic rare region effect in Pr0.5Ca0.5MnO3

“…However, for low band width systems near half doping, the debate is mainly centered around the following competing pictures of charge ordering [10]: 1) CE type charge and magnetic ordering, originally proposed by Goodenough [11]; 2) Zener polaron (ZP) ordering with antiferromagnetic interaction between strong ferromagnetically coupled dimers [12]; 3) Coexistence of both CE type and ZP type ordering [13] or between correlated and uncorrelated polarons [14]. The last two frameworks have the additional advantage of being able to explain away the emergence of ferroelectricity in charge-ordered manganites [13,[15][16][17].…”

Anomalous Ca-Content Dependence of Dielectric Property of Charge Ordered Pr1-xCaxMnO3 as a Signature of Charge-Ordered Phase Modulation

“…The admixture phase can break the inversion symmetry and leads to development of local ferroelectric moment. In fact the direct experimental evidence of subtle macroscopic ferroelectric polarization have recently been found in remnant electrical polarization measurement in Pr1−xCaxMnO3 samples[37,38] while indirect evidence of local ferroelectric moment have confirmed earlier in EFG measurement [34]…”

Anomalous ferroelectric switching dynamics in single crystalline SrTiO3

“…Combining the difference between half hysteresis loops measured in sequence 2 and 3 on one hand and 4 and 5 on the other gives us the complete four-quadrant P SW vs. E hysteresis loop. The capacitance was measured as described in Ref 32 . The temperature dependent polarized Raman Spectroscopy was carried out using STR Raman Spectrometer (Airix Corporation, Japan).…”

“…Therefore, PUND method is a better tool to explore the remanent electric polarization as discussed in our previous report 32 . Instead of rectangular pulses applied in capacitive measurements, here, we have applied triangular pulses so that rate of change of electric field over time should be fairly constant except that for reversal points.…”