Looks nice. Just be aware that in literature the core is usually on the left of the @ and the shell on the right. So in your case I guess it should be Fe2O3@Fe3O4
See for instance Article Al@TiO 2 Core–Shell Nanoparticles for Plasmonic Photocatalysis
Andrea Braga i have performed xrd analysis where i got planes of both haemetite as well as magnetite. further i have performed xps analysis after itching 5 nm every time and after some of itchings i got core fe2o3.