论文标题
在移位电流中量化带内浆果相的量化
Quantization of intra- and inter-band Berry phases in the shift current
论文作者
论文摘要
到目前为止，转移电流的理论是几何而没有拓扑的。这意味着光激发的准粒子的真实空间位移/移位取决于几何浆果相，但是浆果相位未量化为$2π$的合理倍数。我通过引入一类新的拓扑绝缘子来纠正此状态，其谱带拓扑与非中心对称空间组兼容。对于这样的绝缘子，不可能在整个布里群区域中连续调整$ \ boldsymbol {k} $ - 依赖性移位向量为零。适当平均，将移位向量定量为Bravais晶格矢量的合理倍数。即使有宽带隙，频率集成的换档电导率也大大超过$ e^3/h^2 $，并且至少比原型铁电batio $ _3 $的电导率大三个数量级。较大的电导率归因于量化的带内和间浆层相之间的相互作用。特别是，即使对于具有可忽略不计的浆液浆液相的非极化绝缘体，也可以增强带浆液期的拓扑缺陷。
The theory of the shift current is thus far geometrical without being topological. This means that the real-space displacement/shift of a photoexcited quasiparticle depends on the geometric Berry phase, but the Berry phase is not quantized to a rational multiple of $2π$. I rectify this status quo by introducing a new class of topological insulators whose band topology is \textit{only} compatible with a non-centrosymmetric space group. For such insulators, it is impossible to continuously tune the $\boldsymbol{k}$-dependent shift vector to zero throughout the Brillouin zone. Suitably averaged, the shift vector is quantized to a rational multiple of a Bravais lattice vector. Even with wide band gaps, the frequency-integrated shift conductivity greatly exceeds $e^3/h^2$, and is at least three orders of magnitude larger than the conductivity of the prototypical ferroelectric BaTiO$_3$. The large conductivity is attributed to an interplay between quantized intra- and inter-band Berry phases. In particular, topological defects of the inter-band Berry phase can enhance the shift current, even for unpolarized insulators with negligible intra-band Berry phase.
