Spin-polarizing electron beam splitter from crossed graphene nanoribbons

OPEN DATA related to the research publication: S. Sanz, N. Papior, G. Giedke, D. Sánchez-Portal, M. Brandbyge, and T. Frederiksen, Spin-polarizing electron beam splitter from crossed graphene nanoribbons,Phys. Rev. Lett. 129, 037701 (2022) [arXiv:2201.07147] Abstract: Junctions composed of two crossed graphene nanoribbons (GNRs) have been theoretically proposed as electron beam splitters where incoming electron waves in one GNR can be split coherently into propagating waves in two outgoing terminals with nearly equal amplitude and zero back-scattering. Here we scrutinize this effect for devices composed of narrow zigzag GNRs taking explicitly into account the role of Coulomb repulsion that leads to spin-polarized edge states within mean-field theory. We show that the beam-splitting effect survives the opening of the well-known correlation gap and, more strikingly, that a spin-dependent scattering potential emerges which spin polarizes the transmitted electrons in the two outputs. By studying different ribbons and intersection angles we provide evidence that this is a general feature with edge-polarized nanoribbons. A near-perfect polarization can be achieved by joining several junctions in series. Our findings suggest that GNRs are interesting building blocks in spintronics and quantum technologies with applications for interferometry and entanglement.关联该研究论文的开放数据集： S. Sanz、N. Papior、G. Giedke、D. Sánchez-Portal、M. Brandbyge 与 T. Frederiksen，《基于交叉石墨烯纳米带的自旋极化电子分束器》，Phys. Rev. Lett. 129, 037701 (2022) [arXiv:2201.07147] 摘要：由两条交叉石墨烯纳米带（GNRs）构成的结结构此前已被理论提出作为电子分束器，可将单条石墨烯纳米带内的入射电子波相干拆分至两条输出端的传播波中，且振幅近似相等、无反向散射。本文针对窄锯齿型石墨烯纳米带构成的器件细致研究这一效应，在平均场理论框架下明确考量了库仑排斥的作用——该相互作用会产生自旋极化边缘态。我们证明，分束效应在知名的关联能隙开启后仍可存续；更引人注目的是，会出现一种自旋相关散射势，可使两路输出的透射电子产生自旋极化。通过对不同宽度纳米带与交叉角度的研究，我们证实这是边缘极化纳米带的通用特性。通过串联多个结结构，可实现近乎完美的自旋极化。本研究结果表明，石墨烯纳米带是自旋电子学与量子技术中极具潜力的构建模块，可应用于干涉测量与量子纠缠相关领域。