Topological resonance and single-optical-cycle valley polarization in gapped graphene
Topological resonance and single-optical-cycle valley polarization in gapped graphene
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DOI：
10.1103/physrevb.100.115431
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发表时间：
2019-09
影响因子：
3.7
通讯作者：
S. A. Oliaei Motlagh;F. Nematollahi;V. Apalkov;M. Stockman
中科院分区：
文献类型：
--
作者：
S. A. Oliaei Motlagh;F. Nematollahi;V. Apalkov;M. Stockman
对于带隙石墨烯，我们预测，一个强烈的超短（单振荡）圆偏振光脉冲可以诱导大量的导带和大的谷极化。随着带隙的增加，谷极化的幅度从零（对于天然无带隙石墨烯）逐渐增加到单位数量级的值。被激发进入导带的电子的能量带宽可以非常大（对于合理的脉冲幅度$\sim 0.5$ $\mathrm{V/A}$，$\gtrsim 10$ eV）。这些现象是由于拓扑共振效应：拓扑（几何）相位和动力学相位的匹配。具有可调带隙的带隙石墨烯可以用作具有蜂窝通用晶格结构和破缺反转对称性的二维半导体（诸如过渡金属二硫属化物）的方便通用模型。
For gapped graphene, we predict that an intense ultrashort (single-oscillation) circularly-polarized optical pulse can induce a large population of the conduction band and a large valley polarization. With an increase in the bandgap, the magnitude of the valley polarization gradually increases from zero (for the native gapless graphene) to a value on the order of unity. The energy bandwidth of the electrons excited into the conduction band can be very large ($\gtrsim 10$ eV for a reasonable pulse amplitude of $\sim 0.5$ $\mathrm{V/A}$). These phenomena are due to the effect of topological resonance: the matching of the topological (geometric) phase and the dynamic phase. Gapped graphene with tunable bandgap can be used as a convenient generic model of two-dimensional semiconductors with honeycomb generic lattice structures and broken inversion symmetry, such as transition metal dichalcogenides.