We propose to study a novel nanostructure consisting of multi-walled carbon nanotubes continuously filled with a single crystal of Fe3C using total neutron scattering on NIMROD. The high-purity magnetic core, protected from degradation by the carbon layer, displays anomalous magnetic properties including marked steps in the hysteresis curve and reduced coercivity at low temperatures. These are potentially relevant to technological applications including magnetic data storage and hyperthermia cancer therapy; yet their structural causes are unknown. Our data, modelled using PDFgui and RMCprofile refinement, will provide crucial information for understanding the local magnetic and atomic structure that determines this peculiar behaviour. They will also form part of a broader project aimed at developing methods to accurately model total scattering from nanomaterials.