Transport in strained graphene: Interplay of Abelian and axial magnetic fields
Transport in strained graphene: Interplay of Abelian and axial magnetic fields
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DOI：
10.1103/physrevb.108.155426
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发表时间：
2022-12
影响因子：
3.7
通讯作者：
A. Ahmed;Sanjib Das;B. Roy
中科院分区：
文献类型：
--
作者：
A. Ahmed;Sanjib Das;B. Roy
沉浸在外部磁场（$B$）中，弯曲的石墨烯构成了一个理想的桌面设置，表现出时间反演对称性（${\mathcal T}$）破坏阿贝尔（$B$）和${\mathcal T}$保持应变诱导的内部轴向（$B$）磁场的汇合。在这样的系统中，在这里，我们数值计算两端电导（$G$），以及四端和六端霍尔电导（$\sigma_{xy}$）的无自旋费米子。在平坦的石墨烯（$B=0$）上，$B$场在$G=\pm处产生量子化平台|\sigma_{xy}|=（2n+1）e^2/h$，其中$n= 0，1，2，\cdots$。应变诱导的$B$场提高了高朗道能级的二重谷简并，并导致在$G=\pm处形成额外的偶数阶平台|\sigma_{xy}|=（2，4，\cdots）e^2/h$，当$B>B$时。当$B>B$时，$G$也出现了相同的平台序列，而在霍尔棒几何中，$\sigma_{xy}$的数值计算则变得不稳定.在$G=\sigma_{xy}=0$的平台总是出现与电荷密度波序的开始，导致蜂窝晶格的两个子晶格之间的费米密度的交错图案。
Immersed in external magnetic fields ($B$), buckled graphene constitutes an ideal tabletop setup, manifesting a confluence of time-reversal symmetry (${\mathcal T}$) breaking Abelian ($B$) and ${\mathcal T}$-preserving strain-induced internal axial ($b$) magnetic fields. In such a system, here we numerically compute two-terminal conductance ($G$), and four- as well as six-terminal Hall conductivity ($\sigma_{xy}$) for spinless fermions. On a flat graphene ($b=0$), the $B$ field produces quantized plateaus at $G=\pm |\sigma_{xy}|=(2n+1) e^2/h$, where $n=0,1,2, \cdots$. The strain induced $b$ field lifts the two-fold valley degeneracy of higher Landau levels and leads to the formation of additional even-integer plateaus at $G=\pm |\sigma_{xy}|= (2,4,\cdots)e^2/h$, when $B>b$. While the same sequence of plateaus is observed for $G$ when $b>B$, the numerical computation of $\sigma_{xy}$ in Hall bar geometries in this regime becomes unstable. A plateau at $G=\sigma_{xy}=0$ always appears with the onset of a charge-density-wave order, causing a staggered pattern of fermionic density between two sublattices of the honeycomb lattice.