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Ultrathin Interfacial Layer with Suppressed Room Temperature Magnetization in Magnesium Aluminum Ferrite Thin Films



Jacob J. Wisser, Satoru Emori, Lauren Riddiford, Aaron Altman, Peng Li, Krishnamurthy Mahalingam, Brittany T. Urwin, Brandon M. Howe, Michael R. Page, Alexander Grutter, Brian Kirby, Yuri Suzuki


Low-damping magnetic oxide thin films with small thicknesses are essential for efficient insulator spintronic devices, particularly those driven by spin torques effects. Here, we investigate depth-resolved compositional and magnetic properties of epitaxial spinel MgAl0.5Fe1.5O4 (MAFO), which has recently been reported as a promising low-damping insulator. We find that approximately equal}11 nm films give optimal Gilbert damping, with a typical damping parameter of 0.001. While defects due to strain relaxation in the film bulk contribute to increased damping for large thicknesses, damping increase in thinner films is attributed to the presence of a chemically disordered magnetic dead layer at the film/substrate interface. This interfacial dead layer arises from a Fe deficient MAFO layer whose magnetic transition temperature is suppressed below room temperature. Notably, this layer is only about one-sixth the thickness of that found at the interface between yttrium iron garnet films and gadolinium gallium garnet substrates, making MAFO an ideal thin-film insulator for spin-torque applications.
Applied Physics Letters


Spin pumping, spinel, magnetic damping, neutron reflectometry, magnetism, thin film


Wisser, J. , Emori, S. , Riddiford, L. , Altman, A. , Li, P. , Mahalingam, K. , Urwin, B. , Howe, B. , Page, M. , Grutter, A. , Kirby, B. and Suzuki, Y. (2019), Ultrathin Interfacial Layer with Suppressed Room Temperature Magnetization in Magnesium Aluminum Ferrite Thin Films, Applied Physics Letters, [online], (Accessed April 20, 2024)
Created September 23, 2019, Updated October 12, 2021