驱动拓扑绝缘体中的平带形成与手性超导电性
Flat-band formation and chiral superconductivity in driven topological insulators
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中文总结 AI 辅助
研究利用圆偏振光在三维拓扑绝缘体表面Floquet工程出平带或墨西哥帽型能带，该能带可通过纯排斥库仑相互作用支持拓扑超导，结合合适金属栅可实现~7K的超导转变温度并避免维格纳结晶。
中文摘要 AI 辅助
我们证明圆偏振光可用于在三维拓扑绝缘体（3D TI）表面Floquet工程出近平带或墨西哥帽型电子能带，这类能带在合适条件下可通过纯排斥库仑相互作用支持拓扑超导电性。驱动作用不仅能在3D TI表面打开狄拉克锥的能隙，还可用于减小甚至翻转狄拉克点外表面态色散的固有曲率。利用典型3D TI的参数，我们发现平带极限可在合理电场下实现，且通过改变驱动场强度得到的能带，其能量和空间分布与菱面石墨烯在不同位移场下得到的能带相似，而后者近期已被证实存在纯排斥相互作用下的超导情况。我们发现，借助位置合适的屏蔽金属栅，在该装置中可获得$T_c \backsim 7$K的超导转变温度，同时在电子密度范围为$10^{11}-10^{12}/\text{cm}^2$的低电子密度下避免维格纳结晶。
英文摘要
We demonstrate that circularly polarized light can be used to Floquet-engineer nearly flat or Mexican-hat like electronic bands on the surface of three-dimensional topological insulators (3D TIs), which under suitable conditions, can support topological superconductivity via purely repulsive Coulomb interactions. The driving acts not merely by gapping out the Dirac cone on the surface of the 3D TI, but can be used to diminish, and even flip in sign, the intrinsic curvature of the surface state dispersion away from the Dirac point. Using parameters for canonical 3D TIs, we find that the flat band limit is attained for reasonable electric fields and the bands realized by changing the strength of the driving field have a similar energetic and spatial profile to those obtained in rhombohedral graphene under varying displacement field, where the case for superconductivity with purely repulsive interactions has recently been made. We find that, with the aid of appropriately placed screening metallic gate, one can obtain $T_c \sim 7 $K in this setup while avoiding Wigner crystallization for low electron densities in the range of $10^{11}-10^{12}/\text{cm}^2$.
