Abstract
The La0.7Sr0.3CoO3-δ/La0.7Sr0.3MnO3-δ (LSCO/LSMO) bilayer system is an ideal perovskite oxide platform for investigating interface reconstruction and its effect on their magnetic properties. Previous studies have shown that LSCO can separate into magnetic sublayers, which possess distinct trends as the total LSCO thickness increases. In this study, we used polarized neutron reflectometry to quantify changes in the magnetic and chemical depth profiles, and it confirms the formation of ∼12 Å-thick interfacial LSCO and LSMO layers, characterized by a decreased nuclear scattering length density compared to the bulk of the layers. This decrease is attributed to the combined effects of oxygen vacancy formation and interfacial charge transfer, which lead to magnetically active Co2+ ions with ionic radii larger than the Co3+/Co4+ ions typically found in bulk LSCO or single-layer films. The interfacial magnetization values, as well as Co2+ ion and oxygen vacancy concentrations, depend strongly on the LSCO layer thickness. These results highlight the sensitive interplay of the cation valence states, oxygen vacancy concentration, and magnetization at interfaces in perovskite oxide multilayers, demonstrating the potential to tune their functional properties via careful design of their structure.
Original language | English |
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Pages (from-to) | 45437-45443 |
Number of pages | 7 |
Journal | ACS Applied Materials and Interfaces |
Volume | 12 |
Issue number | 40 |
DOIs | |
State | Published - Oct 7 2020 |
Funding
Financial support for this project was provided by the University of California, Multicampus Research Programs and Initiatives grant MR-15-328528, National Science Foundation grant DMR - 1745450, and the U.S. Department of Energy (DOE), Office of Science, Office of Workforce Development for Teachers and Scientists, Office of Science Graduate Student Research (SCGSR) program. The SCGSR program is administered by the Oak Ridge Institute for Science and Education (ORISE) for the DOE. ORISE is managed by Oak Ridge Associated Universities under contract number DE-SC0014664. This research used resources of the ALS, which is a DOE Office of Science User Facility under contract No. DE-AC02-05CH1123. Use of SSRL, SLAC National Accelerator Laboratory, is supported by the U.S. DOE, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. The research performed at ORNL’s Spallation Neutron Source was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy.
Keywords
- charge transfer
- exchange bias
- interface reconstruction
- magnetism
- perovskites
- polarized neutron reflectometry
- thin films