Abstract We show that the second-harmonic generation (SHG) is enhanced in the chiral one-dimensional electron currents in a broad frequency range. The origin of the enhancement is twofold: first, the linear dispersion of the quasiparticles and the associated plasmonic mode as well as the quasi-linear dispersion of plasmon-polariton result in the lift of the phase-matching condition. Moreover, the strong field localization leads to the further increase of the SHG in the structure. The results suggest that the chiral currents localized at the domain walls of magnetic topological insulators can be an efficient source of the second-harmonic signal in the terahertz frequency range.

中文翻译：

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磁拓扑绝缘体畴壁二次谐波产生的宽带增强

摘要 我们表明，二次谐波产生 (SHG) 在宽频率范围内的手征一维电子流中得到增强。增强的起源是双重的：首先，准粒子的线性色散和相关的等离子体模式以及等离子体极化子的准线性色散导致相位匹配条件的提升。此外，强场定位导致结构中SHG的进一步增加。结果表明，位于磁性拓扑绝缘体畴壁处的手征电流可以成为太赫兹频率范围内二次谐波信号的有效来源。