Low-frequency and shot noises in CoFeB/MgO/CoFeB magnetic tunneling junctions
Low-frequency and shot noises in CoFeB/MgO/CoFeB magnetic tunneling junctions
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DOI：
10.1103/physrevb.86.224423
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发表时间：
2012-12
期刊：
影响因子：
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通讯作者：
T. Arakawa;Takahiro Tanaka;K. Chida;S. Matsuo;Y. Nishihara;D. Chiba;K. Kobayashi;T. Ono;A. Fukus
中科院分区：
文献类型：
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作者：
T. Arakawa;Takahiro Tanaka;K. Chida;S. Matsuo;Y. Nishihara;D. Chiba;K. Kobayashi;T. Ono;A. Fukus
研究了自旋阀CoFeB/MgO/CoFeB磁隧道结在低温下的低频和散粒噪声。自由层磁滞回线周围测量的 1/f 噪声表明 1/f 噪声的主要来源是磁涨落，这可以根据涨落-耗散关系进行讨论。观察到随机电报噪声 (RTN) 在两种磁性配置的磁滞回线中对称增强。我们发现这种增强是由自由层中两种磁态之间的波动引起的。尽管 1/f 噪声几乎与磁配置无关，但 RTN 在反并联配置中得到增强。这些发现表明 RTN 存在自旋依赖性激活。散粒噪声揭示了通过晶体 MgO 势垒的自旋相关相干隧道过程。
The low-frequency and shot noises in spin-valve CoFeB/MgO/CoFeB magnetic tunneling junctions were studied at low temperature. The measured 1/f noise around the magnetic hysteresis loops of the free layer indicates that the main origin of the 1/f noise is the magnetic fluctuation, which is discussed in terms of a fluctuation-dissipation relation. Random telegraph noise (RTN) is observed to be symmetrically enhanced in the hysteresis loop with regard to the two magnetic configurations. We found that this enhancement is caused by the fluctuation between two magnetic states in the free layer. Although the 1/f noise is almost independent of the magnetic configuration, the RTN is enhanced in the antiparallel configuration. These findings indicate the presence of spin-dependent activation of RTN. Shot noise reveals the spin-dependent coherent tunneling process via a crystalline MgO barrier.