Spin transport; quantum transport; new materials; topological insulators

自旋传输；

• 批准号: 237560938
• 负责人: Dr. Bernd Beschoten
• 金额: --
• 依托单位: II. Physikalisches Institut A - Physik der kondensierten Materie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2013
• 资助国家: 德国
• 起止时间: 2012-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/237560938?language=en
• 关键词: Spin; transport; quantum; new; materials

The main goal of this project is to explore the spin polarization of surface states in Bi-based topological insulators (TI) using an inverted device structure where the TI is electrically contacted from the bottom rather than from the top surface. This special fabrication method has the ability to significantly improve the TI-to-electrode interface yielding enhanced device performances. We suggest using two kinds of devices: (1) In the first set of devices we mechanically transfer a TI/hBN heterostructure onto Co/MgO and Au electrodes which were prepatterned on a Si++/SiO2 wafer. The ferromagnetic Co/MgO electrode acts as a spin-sensitive detector of the surface spin polarization which probes the spin accumulation at the TI-to-MgO/Co interface. Our devices offer to explore the TI surface spin polarization without disturbing fringe fields which may mask the measured spin voltages. (2) In the second set of devices, we aim to convert the surface spin polarization of the TI into a spin current which we inject from the TI surface into an adjacent graphene layer. This spin current shall be probed away from the TI material non-locally by spin-valve measurements using additional Co/MgO electrodes. In these devices, we expect to probe proximity-induced spin-orbit coupling at the TI-tographene interface. We also propose to use photo current measurements as spin sensitive probes of the TI surface polarization. While several previous photo current experiments only indirectly prove spin contributions by symmetry analysis of the measured polarization dependence, we aim to combine photo current excitation at the TI-to-graphene interface with spin-sensitive electrical read-out.

该项目的主要目标是探索Bi基拓扑绝缘体（TI）的表面态的自旋极化，使用倒置的器件结构，其中TI是从底部而不是从顶部表面电接触。这种特殊的制造方法有能力显着改善钛电极界面产生增强的设备性能。我们建议使用两种类型的器件：（1）在第一组器件中，我们将TI/hBN异质结构机械转移到预先图案化在Si++/SiO2晶片上的Co/MgO和Au电极上。铁磁Co/MgO电极作为表面自旋极化的自旋敏感检测器，其探测在TI到MgO/Co界面处的自旋积累。我们的设备提供探索TI表面自旋极化，而不会干扰边缘场，这可能会掩盖测量的自旋电压。(2)在第二组器件中，我们的目标是将TI的表面自旋极化转换为自旋电流，我们将其从TI表面注入相邻的石墨烯层。应使用额外的Co/MgO电极通过自旋阀测量非局部探测TI材料的自旋电流。在这些器件中，我们期望探测在TI-石墨烯界面处邻近诱导的自旋轨道耦合。我们还建议使用光电流测量作为TI表面极化的自旋敏感探针。虽然之前的几个光电流实验仅通过测量的偏振依赖性的对称性分析间接证明了自旋贡献，但我们的目标是将TI到石墨烯界面处的光电流激发与自旋敏感的电读出结合联合收割机。