Atomic-scale structure and formation of antiphase boundaries in α-Li0.5Fe2.5O4 thin films on MgAl2O4(001) substrates

The occurrence of antiferromagnetic coupling at antiphase domain boundaries (APBs) of ferromagnetic materials holds potential applications for room-temperature spintronic devices. Here, we report formation mechanism and atomic-scale structure properties of APBs in alpha-Li0.5Fe2.5O4 thin films on MgAl2O4 (001) substrates investigated by means of aberration-corrected scanning transmission electron microscopy. The APBs in the alpha-Li0.5Fe2.5O4 films are either conservative or non-conservative. Across the APBs the oxygen sublattice in alpha-Li0.5Fe2.5O4 is maintained, while the stacking sequence of the cation sublattice is interrupted. The propagation of APBs is found to occur in a complex way within the ferromagnetic films, including the dissociation of APBs and the formation of kinks. Importantly, the density of APBs can be tuned by controlling the thickness of the alpha-Li0.5Fe2.5O4 films since the APBs bound interfacial dislocations contributing to film-substrate strain relaxation. Our results evidence that the nano-scale APBs in the alpha-Li0.5Fe2.5O4 films are controllable and stable, which could be promising candidates for applications in nano-spintronic devices. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.