Interfacial magnetism in topological insulator heterostructures

拓扑绝缘体异质结构中的界面磁性

• 批准号: 2604894
• 金额: --
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2604894
• 关键词: Interfacial; magnetism; topological; insulator; heterostructures

Project description:About 5% of electricity is wasted during transmission, while electric appliances convert a large fraction of the electricity into unwanted heat. This project aims at investigating a new class of materials with the potential to overcome dissipation of energy. Three-dimensional topological insulators ("Tis") have an insulating bulk but conductive surfaces, which are topologically protected - a consequence of large spin-orbit coupling and time reversal symmetry. In magnetically doped TIs, the quantum anomalous Hall effect ("QAHE") was predicted and experimentally confirmed in 2013. Similar to the quantum Hall effect ("QHE"), which was observed several decades earlier, chiral, dissipationless transport takes place at the edges of the sample. The QHE is difficult to realise since high magnetic fields and low temperatures are required. The QAHE is much less demanding, being satisfied with the presence of certain magnetic and topological properties of the host materials. The challenge is to find suitable materials which have these properties at technically feasible temperatures, ideally at room temperature.The Project will aim to deliver ground-breaking experimental results on topological magnetic materials, in particular TIs proximity-coupled to AFs, using an integrated, synchrotron- and neutron-based multi-tool approach. It aims at achieving a big leap forward towards the realisation of the QAHE at high temperatures, which will put an end to the need for expensive cooling and external magnetic fields and will be ground-breaking for innovations in energy-efficient electronic devices. We will combine topological insulators with antiferromagnets (AFs) to induce magnetic order in the TIs and achieve a gap-opening in the band structure of the Dirac surface states - requirements for the QAHE and explore the potential for increasing the temperature beyond cryogenic temperatures. AFs benefit from many advantages compared to ferromagnets, such as a higher magnetic ordering temperature and a stronger proximity effect. Furthermore, no magnetic stray fields are produced due to the compensated spin structure of the AF, facilitating the magnetic characterisation of the TI and consequently supporting the optimisation of the materials.The significance of this Project is to expand the operation of the QAHE towards even higher temperatures by AF-TI proximity coupling. We envision to make use of the combined unique capabilities of Diamond and ISIS, and propose a multi-method study of the magnetic properties (XAS/XMCD/XMLD, XPEEM, PNR) and electronic properties (HAXPES, transport).This project is a joint project with the Diamond Light Source (Dr Dirk Backes) and ISIS/STFC (Prof Sean Langridge).This project aligns with EPSRC's research areas "Condensed Matter: Magnetism and Magnetic Materials" and "Spintronics".

项目描述：约5%的电力在传输过程中被浪费，而电器将大部分电力转化为不需要的热量。该项目旨在研究具有克服能量耗散潜力的新型材料。三维拓扑绝缘体（“Tis”）具有绝缘体但导电的表面，其被拓扑保护-大的自旋轨道耦合和时间反演对称性的结果。在磁性掺杂的TI中，量子反常霍尔效应（“QAHE”）在2013年被预测并实验证实。类似于几十年前观察到的量子霍尔效应（“QHE”），手性无耗散传输发生在样品的边缘。QHE很难实现，因为需要高磁场和低温。QAHE的要求要低得多，满足于主体材料的某些磁性和拓扑性质的存在。目前的挑战是找到合适的材料，这些材料在技术上可行的温度下具有这些特性，最理想的是在室温下。该项目的目标是提供突破性的拓扑磁性材料的实验结果，特别是使用集成的，同步加速器和中子为基础的多工具方法的TI接近耦合AF。它旨在实现在高温下实现QAHE的巨大飞跃，这将结束对昂贵冷却和外部磁场的需求，并将成为节能电子设备创新的突破性进展。我们将联合收割机拓扑绝缘体与反铁磁体（AF）相结合，在TI中诱导磁序，并在狄拉克表面态的能带结构中实现间隙开放-QAHE的要求，并探索将温度提高到低温以上的潜力。与铁磁体相比，AF受益于许多优点，例如更高的磁有序温度和更强的邻近效应。此外，由于AF的补偿自旋结构，不会产生杂散磁场，有利于TI的磁性表征，从而支持材料的优化。该项目的意义在于通过AF-TI邻近耦合将QAHE的操作扩展到更高的温度。我们设想利用Diamond和ISIS的组合独特功能，并提出磁性的多方法研究（XAS/XMCD/XMLD，XPEEM，PNR）和电子性质（HAXPES，运输）。该项目是与钻石光源的联合项目（Dirk Backes博士）和ISIS/STFC（Sean Langridge教授）。该项目与EPSRC的研究领域“凝聚态物质：磁性和磁性材料”和“自旋电子学”保持一致。