Sanz Sofia, Papior Nick, Giedke Géza, Sánchez-Portal Daniel, Brandbyge Mads, Frederiksen Thomas
Donostia International Physics Center (DIPC), E-20018 Donostia-San Sebastián, Spain.
DTU Computing Center, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark.
Phys Rev Lett. 2022 Jul 15;129(3):037701. doi: 10.1103/PhysRevLett.129.037701.
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.
由两条交叉的石墨烯纳米带（GNR）组成的结在理论上被提议作为电子束分离器，其中一条GNR中的入射电子波可以相干地分裂成两个输出端中具有几乎相等振幅且背散射为零的传播波。在这里，我们详细研究了由窄锯齿形GNR组成的器件的这种效应，明确考虑了库仑排斥的作用，库仑排斥在平均场理论中导致自旋极化边缘态。我们表明，分束效应在著名的关联能隙打开后仍然存在，更引人注目的是，出现了一个自旋相关的散射势，它使两个输出中的透射电子发生自旋极化。通过研究不同的纳米带和交叉角度，我们提供了证据表明这是边缘极化纳米带的一个普遍特征。通过串联连接几个结可以实现近乎完美的极化。我们的发现表明，GNR在自旋电子学和量子技术中是有趣的构建块，可用于干涉测量和纠缠应用。
