论文标题
二维双层中没有外部磁场的激子绝缘子和超流量
Excitonic insulators and superfluidity in 2D bilayers without external fields
论文作者
论文摘要
我们探索了一个新的平台，用于实现激子绝缘子，即van der waals（VDW）双层，包括2d Janus材料。在先前的研究中，II型杂词已经通过使用外门来调整带对齐方式将激子的绝缘状态带入了激子绝缘状态。相比之下，当前工作的Janus双层代表了内在的激子绝缘子。我们首先进行了从头算的计算，以获得二粒谱带结构，筛选的库仑相互作用以及双层的层间激子结合能。然后，这些源自衍生的数量被用来构建激子冷凝物的BCS样哈密顿量。通过求解平均场间隙方程，我们确定具有绝缘态和超流体特性的16个VDW Janus双层。我们的计算暴露了一类新的高级材料，这些材料可能会在低温下展示新的激子相，并突出层间杂交，自旋轨道耦合和控制其性质的介电筛选之间的微妙竞争。
We explore a new platform for realising excitonic insulators, namely van der Waals (vdW) bilayers comprising 2D Janus materials. In previous studies, Type-II heterobilayers have been brought to the excitonic insulating regime by tuning the band alignment using external gates. In contrast, the Janus bilayers of the current work represent intrinsic excitonic insulators. We first conduct ab initio calculations to obtain the quasiparticle band structures, screened Coulomb interaction, and interlayer exciton binding energies of the bilayers. These ab initio-derived quantities are then used to construct a BCS-like Hamiltonian of the exciton condensate. By solving the mean-field gap equation, we identify 16 vdW Janus bilayers with insulating ground states and superfluid properties. Our calculations expose a new class of advanced materials that are likely to exhibit novel excitonic phases at low temperatures, and highlight the subtle competition between interlayer hybridization, spin-orbit coupling, and dielectric screening that govern their properties.
