Enhanced in-plane anisotropy and ferromagnetic resonance frequency in permalloy films laminated with nitrogen-doped tantalum

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Anthony, Ricky
Hegarty, Margaret
O'Brien, Joe
Rohan, James F.
Ó Mathúna, S. Cian
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Institute of Electrical and Electronics Engineers (IEEE)
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Soft magnetic materials are used in integrated power magnetic devices (such as micro-inductors and microtransformers) to achieve reasonable inductances at frequencies over a few megahertz. However, the out-of-plane (perpendicular) anisotropy, in thick films produced by vapor deposition, worsens the in-plane soft magnetic properties. This paper reports on the nano-lamination of Permalloy (Ni81Fe19) thin films with the introduction of nitrogen-doped tantalum in between to eliminate the out-of-plane anisotropy and improve the in-plane anisotropy. This significantly improves the in-plane soft magnetic properties, reducing the coercivity from 1352 A/m to 25.5 A/m and increasing the anisotropy field from 180 A/m to 660 A/m. The high-frequency permeability was uniform up to 500 MHz, and the ferromagnetic resonance (FMR) frequency was increased to 1 GHz. These properties are ideal for high efficiency magnetic applications at high frequencies and an extended FMR frequency is imperative for gigahertz-range devices.
Soft magnetic materials , Anisotropy , Ferromagnetic resonance frequency , Magnetic laminations , Films , Anisotropic magnetoresistance , Soft magnetic materials , Saturation magnetization , Perpendicular magnetic anisotropy , Magnetic resonance , Coercive force , Ferromagnetic resonance , Laminates , Magnetic anisotropy , Magnetic thin films , Nanocomposites , Nanofabrication , Nitrogen , Permalloy , Soft magnetic materials , Tantalum , Thick films , Vapour deposition
Anthony, R., Hegarty, M., Brien, J. O., Rohan, J. F. and Ó. Mathúna, S. C. (2017) 'Enhanced In-Plane Anisotropy and Ferromagnetic Resonance Frequency in Permalloy Films Laminated With Nitrogen-Doped Tantalum', IEEE Magnetics Letters, 8, pp. 1-4. doi: 10.1109/LMAG.2016.2639471
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