The Misfit Dislocation Core Phase in Complex Oxide Heteroepitaxy

Misfit dislocations form self‐organized nanoscale linear defects exhibiting their own distinct structural, chemical, and physical properties which, particularly in complex oxides, hold a strong potential for the development of nanodevices. However, the transformation of such defects from passive into potentially active functional elements necessitates a deep understanding of the particular mechanisms governing their formation. Here, different atomic resolution imaging and spectroscopic techniques are combined to determine the complex structure of misfit dislocations in the perovskite type La0.67Sr0.33MnO3/LaAlO3 heteroepitaxial system. It is found that while the position of the film–substrate interface is blurred by cation intermixing, oxygen vacancies selectively accumulate at the tensile region of the dislocation strain field. Such accumulation of vacancies is accompanied by the reduction of manganese cations in the same area, inducing chemical expansion effects, which partly accommodate the dislocation strain. The formation of oxygen vacancies is only partially electrically compensated and results in a positive net charge q ≈ +0.3 ± 0.1 localized in the tensile region of the dislocation, while the compressive region remains neutral. The results highlight a prototypical core model for perovskite‐based heteroepitaxial systems and offer insights for predictive manipulation of misfit dislocation properties.The authors thank Dr. Belén Ballesteros for her assistance in TEM experiments with the FEI Tecnai F20 S/TEM microscope. This research was funded by the Spanish MINECO through the “Severo Ochoa” Programme for Centres of Excellence in R&D (SEV‐2015‐0496) and MAT2015‐71664‐R, and the European Union Horizon 2020 research and innovation programme under the Marie Sklodowska‐Curie Grant Agreement No. 645658. ICN2 was supported by the Severo Ochoa program from Spanish MINECO (Grant No. SEV‐2013‐0295) and by the CERCA Programme (Generalitat de Catalunya). The authors also acknowledge financial aid from the Generalitat de Catalunya (2014 SGR 501 and 2014 SGR 1216). N.B. thanks the Spanish MINECO for the financial support through the FPI program. Z.K. is grateful for the support from the Ministry of Education, Science, and Technological Development of the Republic of Serbia through Project No. III45018. B.D.E. and D.W.M. acknowledge support from the Center for Emergent Materials at the Ohio State University, a National Science Foundation Materials Research Science and Engineering Center (Grant No. DMR‐1420451).Peer reviewe