Synthesis and magnetic studies of nanocrystalline Cu2OSeO3, a chiral topological magnet

Topological spin textures, such as magnetic skyrmions observed in certain chiral magnets, are one of the most interesting ordered phases in condensed matter. A skyrmion is a swirling spin structure carrying a topological quantum number. Skyrmions were first observed in MnSi, in 2009, and later observed in Cu 2 OSeO 3 , a chiral antiferromagnet with T N = 58 K that can be synthesized by reacting CuO and SeO2 at 600 ° C . Using a transport agent (typically ammonium chloride) in a chemical vapour transport reaction, single crystals can be grown. As skyrmion lattices may find use in nanotechnological devices, such as data storage systems and in other applications, the magnetic properties of nano-sized compounds deserve to be investigated. The following work presents the synthesis and magnetic studies of the nanocrystalline form of Cu 2 OSeO 3 obtained by an alternative route, thermal decomposition of CuSeO3·2 H2O. This procedure afforded nanostructured samples of reasonable purity ( > 95 % ) . Structural, morphological and magnetic characterization of these samples are reported, aiming to study the effect of nanostructuring on the magnetic phases, in particular the presence and stability of the skyrmionic lattice.