Spin-lattice coupling and frustrated magnetism in Fe-doped hexagonal LuMnO sub(3)

Strong spin-lattice coupling and prominent frustration effects observed in the 50% Fe-doped frustrated hexagonal (h)LuMnO sub(3) are reported. A Neel transition at T sub(N) [approximate] 112 K and a possible spin re-orientation transition at T sub(SR) [approximate] 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 sub(3)cm space group. While the magnetic structure of LuMnO sub(3) belongs to the [Gamma] sub(4) (P6' sub(3)c'm) representation, that of LuFe sub(0.5)Mn sub(0.5)O sub(3) belongs to [Gamma] sub(1) (P6 sub(3)cm) which is supported by the strong intensity for the (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 sub(N) and T sub(SR) which confirms strong spin-lattice coupling. Our results complement the discovery of room temperature multiferroicity in thin films of hLuFeO sub(3) and would give impetus to study LuFe sub(1-x)Mn sub(x)O sub(3) systems as potential multiferroics where electric polarization is linked to giant atomic displacements.