具有翘曲费米面的拓扑绝缘体中非线性霍尔效应的光学激活

中文摘要 AI 辅助

具有六角翘曲费米面的拓扑绝缘体是非线性霍尔效应的天然平台，因为翘曲破坏了反演对称性，同时保持了时间反演对称性。这里我们表明，仅靠这种反演对称性破缺是不够的：尽管翘曲产生了强各向异性的贝里曲率，但保持的三重旋转对称性迫使平衡贝里曲率偶极子恒为零。我们证明，线偏振光可以消除这种对称性障碍：在非共振Floquet体系中，它降低了旋转对称性，同时保持了时间反演对称性，从而产生有限的贝里曲率偶极子，其大小、方向和符号可通过光强和偏振连续调谐。对于实际的Bi$_2$Te$_3$参数，我们表明诱导的贝里曲率偶极子达到约0.03纳米，在实验可及条件下产生微安级的非线性霍尔电流。因此，我们的结果确立了Floquet对称性工程作为在不破坏时间反演对称性的情况下激活拓扑绝缘体表面上对称性禁止的非线性输运的途径。

英文摘要

Topological insulators (TIs) with hexagonally warped Fermi surface are natural platforms for the nonlinear Hall effect, as warping breaks inversion symmetry while preserving time-reversal symmetry (TRS). Here we show that this inversion breaking alone is insufficient: although warping generates a strongly anisotropic Berry curvature, the preserved threefold rotational symmetry forces the equilibrium Berry curvature dipole (BCD) to vanish identically. We demonstrate that linearly polarized light removes this symmetry obstruction: in the off-resonant Floquet regime, it lowers the rotational symmetry while preserving TRS, thereby generating a finite BCD whose magnitude, orientation, and sign are continuously tunable by the light intensity and polarization. For realistic Bi$_2$Te$_3$ parameters, we show that the induced BCD reaches $\sim$0.03~nm, yielding microampere-scale nonlinear Hall currents under experimentally accessible conditions. Our results therefore establish Floquet symmetry engineering as a route to activating the symmetry-forbidden nonlinear transport on TI surfaces without breaking the TRS.

发表机构

• University of Antwerp（安特卫普大学）
• Isfahan University of Technology（伊斯法罕理工大学）

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