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Inhomogeneity of magnetic anisotropy and damping in nanoscale magnetic tunnel junctions

Motoya Shinozaki1,2,*, Junta Igarashi2, Butsurin Jinnai1, Shunsuke Fukami1,3,4,5,6,7,†, Hideo Sato3, and Hideo Ohno1,3,4,5,6

  • *Contact author: motoya.shinozaki@aist.go.jp
  • †Contact author: s-fukami@riec.tohoku.ac.jp
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Phys. Rev. Applied 26, 044089 – Published 29 October, 2026

DOI: https://doi.org/10.1103/l7gr-lj4k

Abstract

We investigate the Gilbert damping constant α and the inhomogeneity of the effective magnetic anisotropy field HKeff in nanoscale magnetic tunnel junctions (MTJs) with various free-layer diameters D, which have two different structures possessing different magnetic properties around the pattern edge. Homodyne-detected ferromagnetic resonance (FMR) is used, allowing to disentangle the inhomogeneous broadening ΔH0 owing to the spatial variation of HKeff from the effects of damping in the linewidth of spectra. We find that ΔH0 increases with decrease in D, while α is almost constant. The degree of the increase in ΔH0 is found to change with the MTJ structure. We show that these results are explained by a model considering the distribution of a demagnetizing field that increases with the decrease in D. The obtained findings provide important insights for the development of nanoscale MTJs with high reliability and high efficiency.

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References (63)

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Phys. Rev. Applied 26, 044089– Published 29 October, 2026
  • Received 26 June 2026
  • Revised 10 September 2026
  • Accepted 23 September 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

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