Cyclotron resonance overtones and near-field magnetoabsorption via terahertz Bernstein modes in graphene
Cyclotron resonance overtones and near-field magnetoabsorption via terahertz Bernstein modes in graphene
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DOI：
10.1038/s41567-021-01494-8
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发表时间：
2022-02-07
期刊：
影响因子：
19.6
通讯作者：
Ganichev, S. D.
中科院分区：
文献类型：
--
作者：
Bandurin, D. A.;Monch, E.;Ganichev, S. D.
在外部磁场中的电子通过回旋共振吸收电磁辐射。偏离这种行为的泛音共振的形式，由于超低磁等离子体激元激发，现在报道的石墨烯。二维电子系统受到垂直磁场吸收电磁辐射通过回旋共振（CR）。在这里，我们报告了石墨烯中这种众所周知的行为的定性偏差。我们的太赫兹光响应的测量揭示了共振突发在CR的主要泛音超过了在普通CR的位置处检测到的信号。光响应的磁场，掺杂水平和样品的几何形状的依赖关系表明，这种异常的起源在于近场磁吸收促进的伯恩斯坦模式-超低磁等离子体激发重塑非本地电子动力学。接近CR谐波，这些模式的特征在于放大辐射吸收的平坦色散和发散等离子体激元态密度。除了进行基本的兴趣，我们的研究结果表明，通过非本地集体模式的辐射吸收可以促进一个强大的光响应的行为可能有用的红外和太赫兹技术。
Electrons in an external magnetic field absorb electromagnetic radiation via cyclotron resonance. Deviations from this behaviour in the form of overtone resonances due to ultraslow magnetoplasmonic excitations are now reported for graphene.Two-dimensional electron systems subjected to a perpendicular magnetic field absorb electromagnetic radiation via cyclotron resonance (CR). Here we report a qualitative deviation from this well-known behaviour in graphene. Our measurements of the terahertz photoresponse reveal a resonant burst at the main overtone of the CR that exceeds the signal detected at the position of the ordinary CR. The dependencies of photoresponse on the magnetic field, doping level and sample geometry suggest that the origin of this anomaly lies in the near-field magnetoabsorption facilitated by the Bernstein modes-ultraslow magnetoplasmonic excitations reshaped by non-local electron dynamics. Close to CR harmonics, these modes are characterized by a flat dispersion and diverging plasmonic density of states that amplify radiation absorption. Besides carrying fundamental interest, our results show that radiation absorption via non-local collective modes can facilitate a strong photoresponse-a behaviour potentially useful for infrared and terahertz technology.