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Engineering Magnetic Interactions in Complex Oxide Heterostructures

Invited

Abstract

Complex oxides possess a wide range of technologically relevant functional properties including ferromagnetism, ferroelectricity, and superconductivity. Furthermore, their interfaces exhibit unexpected functional properties not found in the constituent materials due to structural and chemical changes as well as electronic and magnetic interactions. These unique interfacial effects lead to fundamental differences compared to analogous metallic systems. For example, ferromagnetic (FM)/FM interfaces consisting of magnetically hard La0.7Sr0.3CoO3 (LSCO) and soft La0.7Sr0.3MnO3 (LSMO) display exchange-spring behavior where the hard layer pins the moments of the soft layer, however, the hard/soft magnetic interface does not coincide with the chemical interface.1 Rather, an interfacial LSCO layer forms that is characterized by magnetically active Co2+ ions which couple to the soft LSMO layer. The full characterization of the structural and magnetic properties of the LSCO/LSMO bilayers involves synchrotron-radiation and neutron-scattering based techniques as well as high resolution transmission electron microscopy. We find that the proportion of the Co2+ ion-rich LSCO layer and magnitude of exchange bias shift depends sensitively on parameters such as individual layer thicknesses, epitaxial strain state, BO6 octahedral tilt pattern of the underlying substrate, and stacking order of the layers.2 These results demonstrate how the competing interactions in complex oxides enable intriguing opportunities to tailor functional properties for new, versatile, and energy efficient spintronic devices.
We are grateful to the support by NSF (DMR 1745450), UC MRPI (No. MR-15-328528), and the DOE SCGSR program. This research utilized DOE user facilities including ALS at LBNL, SSRL at SLAC, SNS at ORNL, and EMSL at PNNL.

1B. Li, et al., APL, 105, 202401 (2014)
2B. Li, et al., APL 109, 152401 (2016); A.M. Kane, Y. et al., PRM 3, 014413 (2019); J.P. Byers et al., JAP, 125, 082518 (2019).

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Presenters

  • Yayoi Takamura

    University of California, Davis, Department of Materials Science and Engineering, University of California Davis

Authors

  • Alexander Michael Kane

    University of California, Davis

  • Mingzhen Feng

    University of California, Davis

  • Nolan Ahlm

    University of California, Davis

  • Binzhi Li

    University of California, Davis

  • J. Paige Byers

    University of California, Davis

  • Rajesh V Chopdekar

    Lawrence Berkeley National Laboratory, Lawrence Berkeley National Lab, Advanced Light Source, Lawrence Berkeley National Laboratory

  • Padraic Shafer

    Lawrence Berkeley National Lab, Advanced Light Source, LBNL, Advanced Light Source, Lawrence Berkeley National Laboratory, Advanced Light Source, Advanced Light Source, Lawrence Berkeley National Laboratory, Lawrence Berkeley National Laboratory

  • Alpha T. N'Diaye

    Lawrence Berkeley National Laboratory, Lawrence Berkeley National Lab, Advanced Light Source, Lawrence Berkeley National Laboratory, Adv Light Source LBL

  • Nigel D. Browning

    Imaging Centre at Liverpool, University of Liverpool

  • Valeria Lauter

    Oak Ridge National Laboratory, Thin Films and Nanostructures, Oak Ridge National Laboratory, Neutron Sciences Directorate, Oak Ridge National Laboratory

  • Apurva Mehta

    SLAC National Accelerator Laboratory, Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, SLAC Natl Accel Lab

  • Elke Arenholz

    Lawrence Berkeley National Laboratory, Cornell High Energy Synchrotron Source, Cornell University

  • Yayoi Takamura

    University of California, Davis, Department of Materials Science and Engineering, University of California Davis