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arXiv · 1805.03912

Magnetic excitations in bulk multiferroic two-dimensional triangular lattice antiferromagnet (Lu,Sc)FeO$_3$

J. C. Leiner·Taehun Kim·Kisoo Park·Joosung Oh·T. G. Perring·H. C. Walker·X. Xu·Y. Wang·S. -W. Cheong·Je-Geun Park
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Abstract

Non-collinear two-dimensional triangular lattice antiferromagnets (2D TLAF) are currently an area of very active research due to their unique magnetic properties, which lead to non-trivial quantum effects that experimentally manifest themselves in the spin excitation spectra. Recent examples of such insulating 2D TLAF include (Y,Lu)MnO$_3$, LiCrO$_2$, and CuCrO$_2$. Hexagonal LuFeO3 is a recently synthesized 2D TLAF which exhibits properties of an ideal multiferroic material, partially because of the high spin ($S=5/2$) and strong magnetic super-exchange interactions. We report the full range of spin dynamics in a bulk single crystal of (Lu$_{0.6}$Sc$_{0.4}$)FeO$_3$ (Sc doping to stabilize the hexagonal structure) measured via time-of-flight inelastic neutron scattering. Modeling with linear spin wave theory yields a nearest neighbor exchange coupling of $J$ = 4.0(2) meV (DFT calculations for $h$-LuFeO$_3$ predicted a value of 6.31 meV) and anisotropy values of $K_D$ = 0.17(1) meV (easy plane) and $K_A$~=~-0.05(1)~meV (local easy axis). It is observed that the magnon bandwidth of the spin wave spectra is twice as large for $h$-(Lu,Sc)FeO$_3$ as it is for $h$-LuMnO$_3$.

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J. C. Leiner, Taehun Kim, Kisoo Park, Joosung Oh, T. G. Perring, H. C. Walker, X. Xu, Y. Wang, S. -W. Cheong, Je-Geun Park. 2018-10-11. Magnetic excitations in bulk multiferroic two-dimensional triangular lattice antiferromagnet (Lu,Sc)FeO$_3$. https://doi.org/10.1103/physrevb.98.134412

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