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arXiv · 1402.0905

Magnetic field-induced spontaneous polarization reversal in multiferroic Mn$_{0.85}$Co$_{0.15}$WO$_4$

N. Poudel·K. -C. Liang·Y. -Q. Wang·Y. Y. Sun·B. Lorenz·F. Ye·J. A. Fernandez-Baca·C. W. Chu
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Abstract

The magnetic and ferroelectric properties of the multiferroic system Mn$_{1-x}$Co$_x$WO$_4$ (x=0.135, 0.15, and 0.17) are studied in magnetic fields $H_c$ oriented along the monoclinic $c$-axis. Mn$_{0.85}$Co$_{0.15}$WO$_4$, which is right at the phase boundary between two helical spin structures, exhibits a spontaneous sign change of the ferroelectric polarization when cooled in fields $H_c>$ 25 kOe. The origin of the ferroelectric polarization is studied and two magnetic exchange interactions contributing to the polarization are identified. In Mn$_{0.85}$Co$_{0.15}$WO$_4$ domains of the characteristic helical spin structures, known for x$<$0.15 and x$>$0.15, coexist and form domain boundaries. The contributions of the different domains to the global polarization are determined. The polarization reversal in Mn$_{0.85}$Co$_{0.15}$WO$_4$ can be explained by a combination of various contributions to the polarization and a strong correlation between magnetic domains of different helical spin orders resulting in a smooth transition across the domain walls which preserves the chirality of the spin spiral.

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N. Poudel, K. -C. Liang, Y. -Q. Wang, Y. Y. Sun, B. Lorenz, F. Ye, J. A. Fernandez-Baca, C. W. Chu. 2014-02-04. Magnetic field-induced spontaneous polarization reversal in multiferroic Mn$_{0.85}$Co$_{0.15}$WO$_4$. https://doi.org/10.1103/physrevb.89.054414

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