We investigate spin-wave resonance in nanoscale CoFeB/MgO magnetic tunnel junctions (MTJs) with a perpendicular easy axis and various free-layer sizes. Two types of MTJs are fabricated by different process conditions, and the spin-wave resonance is measured with homodyne-detected ferromagnetic resonance. We focus on the distance between resonance frequencies of the uniform and spin-wave modes as a function of the free-layer size in order to examine the effect of the edge state of MTJs. A marked difference is observed between the two types of MTJs, and the result is consistently reproduced by a model assuming free- or fixed-edge boundary conditions with or without reduced magnetic properties near the pattern edge for each MTJ. The obtained results indicate that the edge state of nanoscale MTJs is crucially affected by the process condition, and spin-wave resonance can serve as a sensitive probe for the edge condition.

中文翻译：

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通过自旋波共振探测纳米级 CoFeB/MgO 磁隧道结的边缘条件

我们研究了具有垂直易轴和各种自由层尺寸的纳米级 CoFeB/MgO 磁性隧道结 (MTJ) 中的自旋波共振。通过不同的工艺条件制造两种类型的 MTJ，并用零差检测铁磁共振测量自旋波共振。我们关注作为自由层尺寸的函数的均匀和自旋波模式的共振频率之间的距离，以检查 MTJ 边缘状态的影响。在两种类型的 MTJ 之间观察到显着差异，并且该结果由假设自由或固定边缘边界条件的模型一致再现，每个 MTJ 的图案边缘附近的磁性降低或不降低。获得的结果表明，纳米级 MTJ 的边缘状态受工艺条件的影响至关重要，