论文标题
在光学驱动的$α$ - $ {T_3} $ lattice中探测拓扑特征
Probing Topological signatures in an optically driven $α$-${T_3}$ Lattice
论文作者
论文摘要
$α$ - $ T_3 $晶格是石墨烯（$α= 0 $）和骰子晶格（$α= 1 $）之间的插值模型，在暴露于圆形极性的圆形极性的lightants light light light light light light littice（$α= 1 $）之间进行拓扑相变。我们研究浆果相介导的散装磁和异常热电响应，以捕获驱动的$α$ -T_3 $晶格的拓扑特征。据透露，与平坦带相关的浆果曲率和轨道磁矩都会在$α= 1/\ sqrt {2} $上改变其各自的符号。当$ 0 <α<1 $ $ $ 0 <α<1 $时，非谐振光会扭曲平坦带，这最终引入了两种独特的分离良好的禁忌间隙，它们的差异频谱中的宽度相等。在禁忌间隙中，轨道磁化强度随着化学电位的线性变化。轨道磁化中线性区域的斜率与$α= 1/\ sqrt {2} $的两侧的Chern号密切相关。我们发现，对于$α> 1/\ sqrt {2} $的坡度约为$α<1/\ sqrt {2} $的两次，这基本上表明跨$α= 1/\ sqrt {2} $的拓扑相变。但是，当化学势在禁止间隙中调谐时，异常的NERNST系数会消失。禁止间隙中的异常霍尔电导率在$α= 1/\ sqrt {2} $的任一侧接近不同的量化值。可以通过实验观察到所有这些拓扑特征。
The $α$-$T_3$ lattice, an interpolation model between the honeycomb lattice of graphene($α=0$) and the dice lattice($α=1$), undergoes a topological phase transition across $α=1/\sqrt{2}$ when exposed to a circularly polarized off-resonant light. We study Berry phase mediated bulk magnetic and anomalous thermoelectric responses in order to capture the topological signatures of a driven $α$-$T_3$ lattice. It is revealed that both the Berry curvature and the orbital magnetic moment associated with the flat band change their respective signs across $α=1/\sqrt{2}$. The off-resonant light distorts the flat band near the Dirac points when $0<α<1$ which eventually introduces two distinct well separated forbidden gaps of equal width in the quasienergy spectrum. The orbital magnetization varies linearly with the chemical potential, in the forbidden gaps. The slopes of the linear regions in the orbital magnetization are closely related to the respective Chern numbers on either side of $α=1/\sqrt{2}$. We find that the slope for $α>1/\sqrt{2}$ is approximately two times of that for $α<1/\sqrt{2}$ which essentially indicates a topological phase transition across $α=1/\sqrt{2}$. However, the anomalous Nernst coefficient vanishes when the chemical potential is tuned in the forbidden gaps. The anomalous Hall conductivity in the forbidden gap(s) approaches different quantized values on either side of $α=1/\sqrt{2}$. All these topological signatures can be observed experimentally.
