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arXiv · 1512.07539

Spin-Lattice Coupling and Frustrated Magnetism in Fe-doped Hexagonal LuMnO3

Harikrishnan S. Nair·Zhendong Fu·C. M. N. Kumar·V. Y. Pomjakushin·Yinguo Xiao·Tapan Chatterji·André M. Strydom
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Abstract

Strong spin-lattice coupling and prominent frustration effects observed in the 50$\%$ Fe-doped frustrated hexagonal ($h$)LuMnO$_3$ are reported. A N\'{e}el transition at $T_{\mathrm N} \approx$ 112~K and a possible spin re-orientation transition at $T_{\mathrm {SR}} \approx$ 55~K are observed in the magnetization data. From neutron powder diffraction data, the nuclear structure at and below 300~K was refined in polar $P6_3cm$ space group. While the magnetic structure of LuMnO$_3$ belongs to the $\Gamma_4$ ($P6'_3c'm$) representation, that of LuFe$_{0.5}$Mn$_{0.5}$O$_3$ belongs to $\Gamma_1$ ($P6_3cm$) which is supported by the strong intensity for the $\mathbf{(100)}$ reflection and also judging by the presence of spin-lattice coupling. The refined atomic positions for Lu and Mn/Fe indicate significant atomic displacements at $T_{\mathrm N}$ and $T_{\mathrm {SR}}$ which confirms strong spin-lattice coupling. Our results complement the discovery of room temperature multiferroicity in thin films of $h$LuFeO$_3$ and would give impetus to study LuFe$_{1-x}$Mn$_x$O$_3$ systems as potential multiferroics where electric polarization is linked to giant atomic displacements.

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Harikrishnan S. Nair, Zhendong Fu, C. M. N. Kumar, V. Y. Pomjakushin, Yinguo Xiao, Tapan Chatterji, André M. Strydom. 2015-12-23. Spin-Lattice Coupling and Frustrated Magnetism in Fe-doped Hexagonal LuMnO3. https://doi.org/10.1209/0295-5075%2F110%2F37007

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