Imaging magnetisation dynamics in nano-contact spin-torque vortex oscillators exhibiting gyrotropic mode splitting
Imaging magnetisation dynamics in nano-contact spin-torque vortex oscillators exhibiting gyrotropic mode splitting
复制标题
表现出陀螺模式分裂的纳米接触自旋扭矩涡旋振荡器中的磁化动力学成像
DOI：
10.1088/1361-6463/aa628a
复制
发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Keatley P
中科院分区：
文献类型：
--
作者：
Keatley P
纳米接触式自旋扭矩涡旋振荡器（STVO）有望在未来的技术应用中作为纳米级微波发射源得到应用。目前，单个STVO的输出功率和相位稳定性与现有的振荡器技术没有竞争力。已经提出了通过磁化动力学的多个纳米接触STVO的同步，以增强微波发射。如果要成功地同步多个STVO，则必须控制设备到设备的变化，例如微波发射的模式分离。在这项工作中，电测量和时间分辨扫描克尔显微镜（TRSKM）的组合被用来演示如何在微波发射STVO的模式分裂有关的磁化动力学所产生的。自由运行的STVO的直流电流的响应仅用于识别设备和偏置磁场的配置，单和多模式的微波发射进行了观察。通过注入小幅度RF电流以锁相自由运行的STVO响应来获取频闪克尔图像。图像显示，具有适度分裂的多模器件的磁化动力学可以通过注入的RF电流来控制，使得它们表现出与单模器件相似的空间特性。显着的分裂被认为是从一个复杂的平衡磁状态，观察克尔图像作为不规则的空间特性的磁化动力学。这种动力学是在远离纳米接触的地方观察到的，因此在电气测量中无法检测到它们的存在。这项工作表明，TRSKM是一个强大的工具，直接观察所产生的STVO表现出复杂的微波发射的磁化动力学。纳米接触周界外的这种动态特性允许更深入地了解共享共同磁性层的多个STVO的最佳锁相的要求。
Nano-contact spin-torque vortex oscillators (STVOs) are anticipated to find application as nanoscale sources of microwave emission in future technological applications. Presently the output power and phase stability of individual STVOs are not competitive with existing oscillator technologies. Synchronisation of multiple nano-contact STVOs via magnetisation dynamics has been proposed to enhance the microwave emission. The control of device-to-device variations, such as mode splitting of the microwave emission, is essential if multiple STVOs are to be successfully synchronised. In this work a combination of electrical measurements and time-resolved scanning Kerr microscopy (TRSKM) was used to demonstrate how mode splitting in the microwave emission of STVOs was related to the magnetisation dynamics that are generated. The free-running STVO response to a DC current only was used to identify devices and bias magnetic field configurations for which single and multiple modes of microwave emission were observed. Stroboscopic Kerr images were acquired by injecting a small amplitude RF current to phase lock the free-running STVO response. The images showed that the magnetisation dynamics of a multimode device with moderate splitting could be controlled by the injected RF current so that they exhibit similar spatial character to that of a single mode. Significant splitting was found to result from a complicated equilibrium magnetic state that was observed in Kerr images as irregular spatial characteristics of the magnetisation dynamics. Such dynamics were observed far from the nano-contact and so their presence cannot be detected in electrical measurements. This work demonstrates that TRSKM is a powerful tool for the direct observation of the magnetisation dynamics generated by STVOs that exhibit complicated microwave emission. Characterisation of such dynamics outside the nano-contact perimeter permits a deeper insight into the requirements for optimal phase-locking of multiple STVOs that share common magnetic layers.
登录
查看更多内容
单点和双点接触自旋力矩振荡器的微磁学
影响因子：
3.2
作者：
G. Hrkac;J. Dean;A. Goncharov;S. Bance;D. Allwood;T. Schrefl;D. Suess;J. Fidler
通讯作者：
J. Fidler
基于纳米收缩的自旋霍尔振荡器
DOI：
10.1109/intmag.2015.7157174
发表时间：
2015
期刊：
2015 IEEE Magnetics Conference (INTERMAG)
影响因子：
--
作者：
V. Demidov;S. Urazhdin;A. Zholud;A. Sadovnikov;S. Demokritov
通讯作者：
S. Demokritov
影响因子：
4.6
作者：
Demidov VE;Urazhdin S;Zholud A;Sadovnikov AV;Slavin AN;Demokritov SO
通讯作者：
Demokritov SO
基于点接触的自旋扭矩振荡器振荡特性变化的实验研究
影响因子：
1.2
作者：
S. Tamaru;D. Ricketts
通讯作者：
D. Ricketts
影响因子：
4
作者：
Hamadeh, A.;Locatelli, N.;Cros, V.
通讯作者：
Cros, V.