3D oxygen vacancy distribution and defect-property relations in an oxide heterostructure

• Published in: Nature communications 2024-06, Vol.15 (1), p.5400-6, Article 5400
• Main Authors: Hunnestad, Kasper A., Das, Hena, Hatzoglou, Constantinos, Holtz, Megan, Brooks, Charles M., van Helvoort, Antonius T. J., Muller, David A., Schlom, Darrell G., Mundy, Julia A., Meier, Dennis
• Format: Article
• Language: English
• Subjects: 147/137; 639/301/119/996; 639/301/930/12; Chemical composition; Defects; Ferrimagnetism; Ferroelectric domains; Ferroelectricity; Free energy; Heat of formation; Heterostructures; Humanities and Social Sciences; Magnetic properties; multidisciplinary; Multiferroic materials; Oxygen; Oxygen content; Physical properties; Science; Science & Technology - Other Topics; Science (multidisciplinary); Superlattices; Tomography; Unconventional superconductivity
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-49437-0

Oxide heterostructures exhibit a vast variety of unique physical properties. Examples are unconventional superconductivity in layered nickelates and topological polar order in (PbTiO 3 ) n /(SrTiO 3 ) n superlattices. Although it is clear that variations in oxygen content are crucial for the electronic correlation phenomena in oxides, it remains a major challenge to quantify their impact. Here, we measure the chemical composition in multiferroic (LuFeO 3 ) 9 /(LuFe 2 O 4 ) 1 superlattices, mapping correlations between the distribution of oxygen vacancies and the electric and magnetic properties. Using atom probe tomography, we observe oxygen vacancies arranging in a layered three-dimensional structure with a local density on the order of 10 14  cm −2 , congruent with the formula-unit-thick ferrimagnetic LuFe 2 O 4 layers. The vacancy order is promoted by the locally reduced formation energy and plays a key role in stabilizing the ferroelectric domains and ferrimagnetism in the LuFeO 3 and LuFe 2 O 4 layers, respectively. The results demonstrate pronounced interactions between oxygen vacancies and the multiferroic order in this system and establish an approach for quantifying the oxygen defects with atomic-scale precision in 3D, giving new opportunities for deterministic defect-enabled property control in oxide heterostructures. Authors apply atom probe tomography to image and quantify the 3D distribution of oxygen vacancies in (LuFeO 3 ) 9 /(LuFe 2 O 4 ) 1 superlattices, linking local variations in chemical composition to the emergent multiferroic properties.