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The crystal structure of Y2CoMnO6. Co2+ (blue) and Mn+4 (light green) ions are surrounded by oxygen polyhedra. Y3+ and O2− are represented as light cyan and red spheres, respectively. The Co-Mn-Co-Mn chains along c-axis form ↑↑-↓↓ spin arrangement.
(a) Room temperature X-ray powder diffraction pattern of Y2CoMnO6 and the Rietveld refinement profile. Observed (o), calculated (red line), background (green line), difference (blue line) are shown along with Bragg position (|). Monoclinic crystal structure in space group P21/n is confirmed. (b) Neutron diffraction pattern at 300 K. Inset compares neutron data at 2.7 K (blue line) and 300 K (black line). A peak at 17.345° relates to antiferromagnetic ordering that is not allowed under P21/n symmetry.
Magnetization versus temperature at 0.005 T (*) and 0.01 T (o) measured under FC and ZFC protocol. Inset (a) shows χ−1 versus temperature with Curie-Weiss fitting. Inset (b) shows ac susceptibility measurement at 7, 77, and 777 Hz. Frequency dependent behaviour is observed below transition temperature.
Electrical polarization is plotted as function of temperature in the presence of 0 and 5 T external field (poling field = 1.5 kV/cm). Inset (a) shows measured pyroelectric current as a function of temperature. Inset (b) shows polarization as a function of temperature for different poling fields (1.5, 1.2, 0.8, 0.4, −0.4, −0.8, −1.2, −1.5 kV/cm). Polarization reversal under negative poling field is confirmed. Inset (c) shows change in pyroelectric current direction as a function of time when temperature is cycled over ±1 K. This confirms genuine ferroelectricity in the compound.
Structural parameters of Y2CoMnO6.
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