Induced Spin Textures in van der Waals Heterostructures

范德华异质结构中的诱导自旋纹理

• 批准号: 279133429
• 负责人: Professor Dr. Guido Burkard
• 金额: --
• 依托单位: Arbeitsgruppe Theoretische Festkörperphysik und Quanteninformation
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/279133429?language=en
• 关键词: Induced; Spin; Textures; van; der

After the discovery of graphene it was soon realized, that graphene is the perfect candidate for spintronics, due to its high mobility, low spin-orbit coupling and small or absent hyperfine fields. By now, spin relaxation lengths longer than 10 micrometers have been demonstrated. Although the results are still far from expectations, the achieved values already make graphene an ideal platform to transfer spin information. The key question at the present stage, how the manipulation of spin can be achieved with graphene devices. In this proposal we will investigate novel routes to add electric and magnetic control over the spin by introducing different spin textures in graphene. Spin textures are induced by developing various 2D proximity heterostructures: First, using magnetic insulators exchange interaction will be induced in graphene and in topological insulators. This will be confirmed by anomalous Hall measurements. Moreover, the magnetic insulator substrates will also allow magnetic gating of the spin-current. Second, spin-orbit interaction (SOI) will be induced in graphene by the proximity of other 2D materials. These materials include topological insulators, transition metal dichalcogenids, and novel 2D materials, with huge spin-orbit coupling, like BiTeI. The induced SOI can enable electrical control of the spin-direction. The presence of SOI will be tested by weak localization, and spin-Hall measurements. It is also predicted, that if the proper SO terms are present in graphene, it can acquire topological properties and turn into the quantum spin-Hall phase. Moreover, new 2D materials, like BiTeI will be interesting for the field of Spintronics by themselves and these materials will also give new building blocks for producing Van der Waals heterostructures. Finally, we will introduce real-space textures into graphene by using metallic superstructures. For this, ferromagnetic and superconducting structures will be fabricated on top of graphene, separated by few layers of h-BN. Here, the stray field of the nanomagnets will be used to induce topologically interesting structures, such as skyrmions. The superconducting electrodes on top of graphene will suppress the magnetic fields due to Meissner effect, and the tailoring of local magnetic fields will be possible. These local fields will be used for spintronics and electron-optical experiments. To achieve our goals we will produce proximity structures based on Van der Waals pick-up technique, and will develop advanced fabrication methods, like point-contacts to encapsulated graphene, or metallic superstructures separated from graphene by few layers of h-BN. The experiments will be supported by DFT and transport calculations. The methods and goals outlined in this proposal will bring graphene based future spintronics applications closer.

在石墨烯被发现后，人们很快意识到石墨烯具有高迁移率、低自旋轨道耦合和小或不存在的超细场，是自旋电子学的完美候选者。到目前为止，已经证明了超过10微米的自旋弛豫长度。尽管结果与预期相差甚远，但已经实现的价值已经使石墨烯成为传递自旋信息的理想平台。现阶段的关键问题是，如何用石墨烯器件来实现自旋的操纵。在本提案中，我们将研究通过在石墨烯中引入不同的自旋结构来增加自旋的电和磁控制的新途径。自旋织构是通过开发各种二维接近异质结构来诱导的：首先，利用磁性绝缘体在石墨烯和拓扑绝缘体中诱导交换相互作用。这将通过异常霍尔测量得到证实。此外，磁性绝缘体衬底也将允许自旋电流的磁门控。其次，石墨烯中的自旋轨道相互作用（SOI）将被其他二维材料的接近所诱导。这些材料包括拓扑绝缘体、过渡金属二硫族化合物和具有巨大自旋轨道耦合的新型二维材料，如BiTeI。诱导的SOI可以实现自旋方向的电气控制。SOI的存在将通过弱局域化和自旋霍尔测量来检验。我们还预测，如果石墨烯中存在适当的SO项，它可以获得拓扑性质并转变为量子自旋霍尔相。此外，新的二维材料，如BiTeI，本身就会对自旋电子学领域产生兴趣，这些材料也将为产生范德华异质结构提供新的基石。最后，我们将通过金属超结构将实空间纹理引入石墨烯。为此，铁磁性和超导结构将在石墨烯上制造，由几层氢氮化硼隔开。在这里，纳米磁体的杂散场将被用来诱导拓扑上有趣的结构，如skyrmions。石墨烯上的超导电极由于迈斯纳效应抑制磁场，使局部磁场的裁剪成为可能。这些局部场将用于自旋电子学和电子光学实验。为了实现我们的目标，我们将基于范德华拾取技术生产接近结构，并将开发先进的制造方法，如与封装石墨烯的点接触，或通过几层h-BN与石墨烯分离的金属超结构。实验将得到DFT和输运计算的支持。本提案中概述的方法和目标将使基于石墨烯的未来自旋电子学应用更加接近。