Evolution of spin-wave modes in magnetic tunnel junction nanopillars
Evolution of spin-wave modes in magnetic tunnel junction nanopillars
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DOI：
10.1103/physrevb.82.100410
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发表时间：
2010-09
影响因子：
3.7
通讯作者：
Z. Zeng;K. H. Cheung;HongWen Jiang;I. Krivorotov;J. Katine;V. Tiberkevich;A. Slavin
中科院分区：
文献类型：
--
作者：
Z. Zeng;K. H. Cheung;HongWen Jiang;I. Krivorotov;J. Katine;V. Tiberkevich;A. Slavin
采用自旋矩驱动的铁磁共振方法研究了不同半短轴和半长轴纵横比的椭圆形MgO基磁性隧道结（MTJ）纳米柱中自旋波的模式结构.我们发现，在小AR样本中，只存在一个准均匀进动模式，而在大AR样本中，进动演变为多个模式，即，同时观察到一个准均匀模和一个附加非均匀模。空间非均匀模是一种自旋波模，它局限于边缘区域，这可以通过考虑横向边界处的钉扎条件来很好地理解。非均匀模式的出现导致MTJ纳米柱中临界开关电流密度的增加。
We use spin-torque-driven ferromagnetic resonance to study the mode structure of spin waves in elliptically-shaped MgO-based magnetic tunnel junction (MTJ) nanopillars with different aspect ratios (AR) of a semiminor axes ofand semimajor axes of. We find that only one quasiuniform precession mode exists in the small AR samples, whereas, in the samples with large ARs, precession evolves into multiple modes, i.e., a quasiuniform mode and an additional nonuniform mode are simultaneously observed. The spatially nonuniform mode is a spin-wave mode localized in the edge regions, which can be well understood by considering the pinning conditions at the lateral boundaries. The appearance of the nonuniform modes results in the increase in the critical switching current densityin MTJ nanopillars.