Bias-driven high-power microwave emission from MgO-based tunnel magnetoresistance devices
Bias-driven high-power microwave emission from MgO-based tunnel magnetoresistance devices
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DOI：
10.1038/nphys1036
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发表时间：
2008-10-01
期刊：
影响因子：
19.6
通讯作者：
Watanabe, Naoki
中科院分区：
文献类型：
--
作者：
Deac, Alina M.;Fukushima, Akio;Watanabe, Naoki
自旋极化电流和铁磁层之间的自旋动量转移可以诱导稳态磁化进动，并且最近被提出作为用于雷达和电信应用的无处不在的射频器件的工作原理。然而，到目前为止，工业上有吸引力的原型的开发一直受到无法确定可以提供足够动力的系统的阻碍。在这里，我们证明，微波信号与设备兼容的输出功率水平可以产生从一个单一的磁性隧道结的横向尺寸为100纳米，7个数量级小于传统的射频振荡器。我们发现，在MgO磁性隧道结的自旋极化电流对局部磁化引起的垂直扭矩可以达到25%的面内自旋扭矩项，虽然表现出不同的偏置依赖性。这两个结果对比与全金属结构，以前的研究，反映了从根本上不同的传输机制，在两种类型的结构上获得的结果。
Spin-momentum transfer between a spin-polarized current and a ferromagnetic layer can induce steady-state magnetization precession, and has recently been proposed as a working principle for ubiquitous radio-frequency devices for radar and telecommunication applications. However, so far, the development of industrially attractive prototypes has been hampered by the inability to identify systems that can provide enough power. Here, we demonstrate that microwave signals with device-compatible output power levels can be generated from a single magnetic tunnel junction with a lateral size of 100 nm, seven orders of magnitude smaller than conventional radio-frequency oscillators. We find that in MgO magnetic tunnel junctions the perpendicular torque induced by the spin-polarized current on the local magnetization can reach 25% of the in-plane spin-torque term, although showing a different bias dependence. Both findings contrast with the results obtained on all-metallic structures, previously investigated, reflecting the fundamentally different transport mechanisms in the two types of structure.