Unraveling the sign reversal of the anomalous Hall effect in ferromagnet/heavy-metal ultrathin films
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Date
2023-03-01
Journal Title
Journal ISSN
Volume Title
Publisher
American Physical Society
Abstract
The sign reversal in the anomalous Hall effect (AHE) that occurs for material offers great prospects for AHE-based spintronic devices design. However, the mechanisms are still controversial in ultrathin ferromagnetic/heavy metal thin film systems due to the complicatedly interfacial effects. Here, we investigate the AHE sign reversal in ultrathin ferromagnetic Mn2CoAl/Pd films, a system which has shown unusual AHE, significant spin-orbit coupling, and magnetic texturing. Element-sensitive cross-sectional STEM imaging and the depth-resolved magnetization profile from polarized neutron reflectometry identifies the presence of a second ferromagnetic layer from intermixed Co-Pd. To quantitatively explain the sign reversal of the AHE, we build a model based on two contributions, ferromagnetic Mn2CoAl and the intermixed CoPd layer. We also clarify that contributions to the AHE from magnetic proximity and spin Hall effect are negligible. Our work demonstrates that interfacial alloying can be a critical factor and provides insightful methods to determine the origins of the AHE in ferromagnet/heavy-metal thin film systems. © 2024 American Physical Society.
Description
Keywords
Hall effect, Ferromagnetism, Heavy metals, Thin Films, Materials, Neutron reflectors, Spin
Citation
Zhang, Y., Cortie, D., LaGrange, T., Lee, W., Butler, T., Ludbrook, B., & Granville, S. (2023). Unraveling the sign reversal of the anomalous Hall effect in ferromagnet/heavy-metal ultrathin films. Physical Review B, 107(9), 094408. doi:10.1103/PhysRevB.107.094408