Data archive of Proximity effects in graphene on monolayers of transition-metal phosphorus trichalcogenides MPX3

We investigate the electronic band structure of graphene on a series of two-dimensional magnetic transition -metal phosphorus trichalcogenide monolayers, MPX3 with M = {Mn,Fe,Ni,Co} and X = {S,Se}, with first-principles calculations. A symmetry-based model Hamiltonian is employed to extract orbital parameters and sublattice resolved proximity-induced exchange couplings (lambda(A)(ex) and lambda(B)(ex)) from the low-energy Dirac bands of the proximitized graphene. Depending on the magnetic phase of the MPX3 layer (ferromagnetic and three antiferromagnetic ones), completely different Dirac dispersions can be realized with exchange splittings ranging from 0 to 10 meV. Remarkably, not only the magnitude of the exchange couplings depends on the magnetic phase, but also the global sign and the type. Important, one can realize uniform (lambda(A)(ex) approximate to lambda(B)(ex)) and staggered (lambda(A)(ex) approximate to -lambda(B)(ex)) exchange couplings in graphene. From selected cases we find that the interlayer distance, as well as a transverse electric field, are efficient tuning knobs for the exchange splittings of the Dirac bands. More specifically, decreasing the interlayer distance by only about 10%, a giant fivefold enhancement of proximity exchange is found, while applying few V/nm of electric field, provides tunability of proximity exchange by tens of percent. We have also studied the dependence on the Hubbard U parameter and find it to be weak. Moreover, we find that the effect of SOC on the proximitized Dirac dispersion is negligible compared to the exchange coupling.

本研究探讨了石墨烯在一系列二维磁性过渡金属磷化物三硫族化合物单层（MPX3，其中M = {Mn,Fe,Ni,Co}且X = {S,Se}）上的电子能带结构，通过第一性原理计算进行。采用基于对称性的模型哈密顿量，从邻近化石墨烯的低能狄拉克带中提取轨道参数以及亚晶格分辨的邻近诱导交换耦合（lambda(A)(ex)和lambda(B)(ex)）。根据MPX3层的磁性相（铁磁和三个反铁磁相），可以实现完全不同的狄拉克色散，交换分裂范围为0至10毫电子伏特。值得注意的是，交换耦合的幅度不仅依赖于磁性相，还包括全局符号和类型。重要的是，可以在石墨烯中实现均匀（lambda(A)(ex)约等于lambda(B)(ex)）和错位（lambda(A)(ex)约等于-lambda(B)(ex)）交换耦合。从选定的案例中我们发现，层间距离以及横向电场是有效调节狄拉克带交换分裂的旋钮。具体而言，仅将层间距离减少约10%，邻近交换就出现了巨大的五倍增强，而施加几伏每纳米的横向电场，则能提供数十个百分点的邻近交换调节能力。我们还研究了Hubbard U参数的依赖性，并发现其影响较弱。此外，我们发现与交换耦合相比，自旋轨道耦合（SOC）对邻近化狄拉克色散的影响可以忽略不计。