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
Department of Materials Science and Engineering, NTNU Norwegian University of Science and Technology, Trondheim, 7491, Norway.
Acoustics Group, Department of Electronic Systems, NTNU Norwegian University of Science and Technology, Trondheim, 7491, Norway.
Nat Commun. 2024 Jun 26;15(1):5400. 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)/(SrTiO) 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)/(LuFeO) 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 10cm, congruent with the formula-unit-thick ferrimagnetic LuFeO 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 and LuFeO 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.
氧化物异质结构展现出各种各样独特的物理性质。例如层状镍酸盐中的非常规超导性以及（PbTiO）/（SrTiO）超晶格中的拓扑极性序。尽管很明显氧含量的变化对于氧化物中的电子关联现象至关重要，但量化其影响仍然是一项重大挑战。在此，我们测量了多铁性（LuFeO）/（LuFeO）超晶格中的化学成分，绘制了氧空位分布与电学和磁学性质之间的相关性。使用原子探针断层扫描技术，我们观察到氧空位排列成层状三维结构，局部密度约为10cm，与化学式单元厚度的亚铁磁性LuFeO层一致。空位有序化是由局部降低的形成能促进的，并且分别在稳定LuFeO和LuFeO层中的铁电畴和亚铁磁性方面起关键作用。结果表明该系统中氧空位与多铁性序之间存在显著相互作用，并建立了一种在三维空间中以原子尺度精度量化氧缺陷的方法，为氧化物异质结构中基于确定性缺陷的性能控制提供了新机会。
