Diffuse Scattering in The Chiral Magnet BaCoSiO₄

In certain chiral magnets, a chiral arrangement of magnetic spins breaks both time reversal and spatial inversion symmetry, forming a toroidal moment. This symmetry breaking allows for the magnetoelectric effect, making these materials promising candidates for device applications. In BaCoSiO₄, Co ions form hexagonal layers in which magnetic interactions between the nearest five Co neighbors, as well as the antisymmetric DM interaction, are all important, leading to a complicated competition between interactions on this frustrated lattice. The ground state structure can be explained by a trimerization of Co ions into toroidal moments which form three interpenetrating sublattices, one of which has a toroidal moment opposite to the other two. Along with the frustration due to antiferromagnetic interactions within triangular trimers, there is structural short-range order which may contribute to additional frustration. In this talk, I will present diffuse scattering results which give insight into the short range magnetic and structural order within the material. Modeling both types of short-range order within the paramagnetic phase will improve our understanding of this exotic magnet.<br/>The research was supported by the U.S. Department of Energy (DOE), Early Career Research Program Awards KC0402020 and KC0402010, and used resources at the HFIR and SNS, DOE Office of Science User Facilities operated by ORNL.