Controlling Magnetization Vector Depth Profiles of La_0.7Sr_0.3CoO₃/La_0.7Sr_0.3MnO₃ Exchange Spring Bilayers via Interface Reconstruction

Abstract

The La 0.7 Sr 0.3 CoO 3-/ La 0.7 Sr 0.3 MnO 3-(LSCO/LSMO) bilayer system is an ideal perovskite oxide platform for investigating electronic interface reconstruction and its effect on the magnetic properties. Previous studies have shown 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 to 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 Co 2+ ions with ionic radii larger than the Co 3+ /Co 4+ ions typically found in bulk LSCO or single layer films. The interfacial magnetization values, as well as Co 2+ 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.

Inferface Magnetization Phenomena in Epitaxial Thin Fe3O4/CoxFe3–xO4 Bilayers

“…Such behavior has also been reported for CFO/Fe 3 O 4 bilayers grown by PLD on MgAl 2 O 4 . Furthermore, a recent work on complex La 0.7 Sr 0.3 CoO 3 /La 0.7 Sr 0.3 MnO 3 exchange bilayers found both increased and decreased Co interface magnetization on the dependence of the LSCO thickness . A thickness-dependent change of the magnetic exchange coupling has also been investigated in Fe/Sm bilayers, and also very recently a thickness-dependent magnetic proximity effect has been found for topological-insulator/ferromagnet bilayers .…”

Cation and anion topotactic transformations in cobaltite thin films leading to Ruddlesden-Popper phases

“…The AG-P sample agrees with literature data for mixed valence Co 3+ /Co 4+ ion in octahedral coordination. [54,55] The OD-P sample shows only subtle changes compared the AG-P sample in the form of slightly less defined spectral features. On the other hand, the XA spectra of the highly reduced phases (BM, NP, and RP) show clear signatures of Co 2+ ions in octahedral coordination with subtle differences in the intensities of the three main spectral features denoted with (A)-(C) dotted lines.…”

Complementary Insights from Neutron and Resonant X‐Ray Reflectometry for the Study of Perovskite Transition Metal Oxide Heterostructures

“…These requirements are met at several instruments around the globe, where it is possible to perform NR of oxide heterostructures. Some recent examples come from studies carried out at large-scale facilities such as FRM II, [35][36][37] ILL, [38] SINQ, [39] ISIS, [40] SNS, [41,42] and NIST. [43][44][45] To demonstrate this important, complementary aspect of Xrays and neutrons, we show simulations for a hypothetical SrVO 3 =SrCrO 3 SL structure in Figure 2.…”

“…These requirements are met at several instruments around the globe, where it is possible to perform NR of oxide heterostructures. Some recent examples come from studies carried out at large‐scale facilities such as FRM II, [ 35–37 ] ILL, [ 38 ] SINQ, [ 39 ] ISIS, [ 40 ] SNS, [ 41,42 ] and NIST. [ 43–45 ]…”