High-temperature ferroelectric order and magnetic field-cooled effect driven magnetoelectric coupling in R2BaCuO5 (R= Er, Dy, Sm)

Abstract

The high-temperature ferroelectric order and a remarkable magnetoelectric effect driven by the magnetic field cooling are reported in R2BaCuO5 (R = Er, Dy, Sm) series. The ferroelectric (FE) orders are observed at much higher temperatures than their magnetic orders for all three members. The value of FE Curie temperature (TF E ) is considerably high as ∼ 235 K with the polarization value (P ) of ∼ 1410 µC/m 2 for a 4 kV/cm poling field in case of Er2BaCuO5, whereas the values of TF E and P are also promising as ∼ 232 K and ∼ 992 µC/m 2 for Dy2BaCuO5, and ∼ 184 K and ∼ 980 µC/m 2 for Sm2BaCuO5. The synchrotron diffraction studies of Dy2BaCuO5 confirm a structural transition at TF E to a polar P na21 structure, which correlates the FE order. An unusual magnetoelectric coupling is observed below the R order for Er and Dy compounds and below the Cu order for Sm compound, when the pyroelectric current is recorded only with the magnetic field both in heating and cooling cycles i.e. typical magnetic field cooled effect. The magnetic field cooled effect driven emergence of polarization is ferroelectric in nature, as it reverses due to the opposite poling field. The unexplored R2BaCuO5 series attracts the community for large TF E , high P value, and strange magnetoelectric consequences.