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arXiv · 1708.02931

Ferroelectricity of structural origin in spin-chain compounds Ca$_3$Co$_{2-x}$Mn$_x$O$_6$

J. Shi·J. D. Song·J. C. Wu·X. Rao·H. L. Che·Z. Y. Zhao·H. D. Zhou·J. Ma·R. R. Zhang·L. Zhang·X. G. Liu·X. Zhao·X. F. Sun
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Abstract

We report a systematic study of the structure, electric and magnetic properties of Ca$_3$Co$_{2-x}$Mn$_x$O$_6$ single crystals with $x =$ 0.72 and 0.26. The DC and AC magnetic susceptibilities display anomalies with characteristic of the spin freezing. The crystals show ferroelectric transition at 40 K and 35 K ($T_{FE}$) for $x =$ 0.72 and 0.26, respectively, with a large value of 1400 $μ$C/m$^2$ at 8 K for electric polarization ($P_c$) along the spin-chain ($c$-axis) direction. Interestingly, the electric polarization perpendicular to the chain direction ($P_{ab}$) can also be detected and has value of 450 and 500 $μ$C/m$^2$ at 8 K for the $x =$ 0.72 and 0.26 samples, respectively. The specific heat and magnetic susceptibility show no anomaly around $T_{FE}$, which means that the electric polarization of these samples has no direct relationship with the magnetism. The X-ray diffraction and the Raman spectroscopy indicate that these samples may undergo Jahn-Teller distortions that could be the reason of electric polarization.

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J. Shi, J. D. Song, J. C. Wu, X. Rao, H. L. Che, Z. Y. Zhao, H. D. Zhou, J. Ma, R. R. Zhang, L. Zhang, X. G. Liu, X. Zhao, X. F. Sun. 2017-08-09. Ferroelectricity of structural origin in spin-chain compounds Ca$_3$Co$_{2-x}$Mn$_x$O$_6$. https://doi.org/10.1103/physrevb.96.064112

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