Proposal for an active electromagnetic metamaterial based on spin-torque oscillators
Proposal for an active electromagnetic metamaterial based on spin-torque oscillators
复制标题
DOI：
10.1103/physrevb.87.155102
复制
发表时间：
2012-12
影响因子：
3.7
通讯作者：
G. Tatara;H. Ueda;K. Taguchi;Y. Sasaki;Miyuki Nishijima;A. Takeuchi
中科院分区：
文献类型：
--
作者：
G. Tatara;H. Ueda;K. Taguchi;Y. Sasaki;Miyuki Nishijima;A. Takeuchi
我们理论上提出了一种通过使用自旋扭矩振荡器来实现 GHz 频率电磁辐射的活性材料。放大的来源是注入电流提供给磁化的能量。我们表明，接近于电流驱动磁化的谐振，对于两个圆偏振中的任何一个，磁导率的虚部实际上变为负值，导致折射率的虚部为负。此外，折射率的实部也受电流控制。因此，我们的系统实现了有源滤波器以获得圆偏振辐射和/或具有负折射率的电磁超材料，两者都是电控制的。
We propose theoretically an active material for electromagnetic radiation with frequency of GHz by use of spin-torque oscillators. The origin of the amplification is the energy supplied to the magnetization by the injected current. We show that close to a resonance with current-driven magnetization, the imaginary part of magnetic permeability becomes indeed negative for either of the two circular polarizations, resulting in negative imaginary part of refractive index. Besides, the real part of the refractive index is also manipulated by the current. Our system thus realizes an active filter to obtain circular polarized radiation and/or an electromagnetic metamaterial having negative refractive index, both controlled electrically.