Effect of Oxygen Stoichiometry on the Magnetization Profiles and Negative Magnetization in LSMO Thin Films

Published

September 14, 2019

Author(s)

Robbyn Trappen, Alexander Grutter, Chih-Yeh Huang, Aubrey Penn, Navid Mottaghi, Saeed Yousefi, Allison Haertter, Shalini Kumari, James LeBeau, Brian Kirby, Mikel B. Holcomb

Abstract

The depth dependent magnetization in thin film oxygen stoichiometric and oxygen deficient La_0.7Sr_0.3MnO₃ is investigated by using polarized neutron reflectivity. The stoichiometric sample shows enhanced interfacial magnetization relative to the rest of the film. The oxygen deficient sample exhibits a reduced average magnetization from the optimized recipe. Both films show regions of suppressed magnetization at the surface regardless of growth pressure. The oxygen stoichiometric film does not show an interfacial dead layer whereas the oxygen deficient film exhibits a dead layer whose thickness changes with temperature. At low applied field we observe striking differences in the depth dependence of the magnetic ordering, with the oxygen deficient film exhibiting exchange-spring behavior, while the stoichiometric film shows a constant magnetization direction across the film. These results suggest that the incorporation of oxygen vacancies during growth leads to an accumulation of vacancies at the interface which is enhanced at higher temperature due to increased oxygen mobility, creating a region of reduced magnetism which couples to the rest of the film. These results offer insight into the complex behavior and role of oxygen vacancies in the magnetism of these systems. Additionally, the study reveals further details of the negative magnetization in La_0.7Sr_0.3MnO₃ reported in previous studies which are discussed here.

Citation

Journal of Applied Physics

Volume

126

Issue

10

Pub Type

Journals

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Keywords

Magnetism, interface, oxide, film, perovskite, neutron reflectometry

Citation

Trappen, R. , Grutter, A. , Huang, C. , Penn, A. , Mottaghi, N. , Yousefi, S. , Haertter, A. , Kumari, S. , LeBeau, J. , Kirby, B. and Holcomb, M. (2019), Effect of Oxygen Stoichiometry on the Magnetization Profiles and Negative Magnetization in LSMO Thin Films, Journal of Applied Physics, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=928233 (Accessed October 11, 2024)