Surface/Interface Phenomena and Topological Order in Emerging Quantum Materials

非技术摘要：近年来，人们对一类被称为拓扑绝缘体(TI)的新兴新材料越来越感兴趣，这些材料在其表面/界面上显示出意想不到的量子性质。这导致了量子科学的巨大进步，并为未来的量子设备带来了潜力，这些设备可以高效地存储和传输信息。这些新材料可以无耗散地携带电流，并能够增强现有技术的性能，如自旋电子学(用于计算机数据存储、通信和传感)。另一种与拓扑相关的现象是一种被称为Majorana约束态(MBS)的新型量子态，它可以通过将具有不同物理现象(拓扑、超导、磁性)的材料结合在一起而出现在TIS中，这可能导致未来高度容错的量子计算。在这个项目中，学生和青年科学家获得了许多先进领域的知识和培训，并推动了物理和材料科学的前沿。有可能为建立高能效的量子电子学奠定基础，从而彻底改变未来的信息技术。技术摘要：通过与铁磁绝缘体的邻近耦合，展示了二维量子相干性质以及界面铁磁性对高温的意外稳定，促使研究：i)在更高的温度下，铁磁TI中出现量子相干性质，ii)当与磁性绝缘体混合时，具有邻近感应带隙的TIS中自旋极化手性电流的量子行为，以及iii)通过隧道光谱探测磁性TI边缘传导通道中的非传统超导配对、电子自旋极化和量子相干性。这些目标是基于我们之前广泛的、与薄膜异质结构特性相关的多学科知识，使用最先进的分子束外延系统用于薄膜生长和测量设施，包括利用国家设施对界面进行原子级表征。在这项计划下，计划对学生(包括高中生暑期计划)和年轻科学家在量子相干拓扑驱动现象所支配的领域进行教育和培训。

Non-Technical Abstract:In recent years interest is increasing in a class of emerging new materials called topological insulators (TI) displaying unexpected quantum properties at their surfaces/interfaces. This has led to vast advancement in quantum science, and with potential for future quantum devices that can be energy efficient for information storage and transmission. These new materials can carry current without dissipation and are capable of enhancing the performance in existing technology such as spintronics (used in computer data storage, communication and sensing). Another topology related phenomenon is a new type of quantum state called Majorana bound states (MBS) that can appear in TIs by combining materials with different physical phenomena (topology, superconductivity, magnetism), which may lead to future highly fault-tolerant quantum computing. In this project, students as well as young scientists acquire knowledge and train in many advanced areas, as well as push the frontiers of physics and material science. There is potential to lay the foundation for establishing energy efficient quantum electronics to revolutionize the future information technology. Instruments, patents and knowledge developed during this research would be made available to companies.Technical Abstract:The demonstration of two-dimensional quantum coherent properties and unexpected stabilization of interfacial ferromagnetism to much higher temperatures in TI by proximity coupling to a ferromagnetic insulator, has prompted the investigation: i) to reach the occurrence of quantum coherent properties in a ferromagnetic TI at a higher temperatures, ii) the quantum behavior of spin polarized chiral current in TIs with proximity induced gap when hybridized with a magnetic insulator, and iii) probe unconventional superconducting pairing, the electron spin polarization and quantum coherence in the edge conduction channel of magnetic TI by tunneling spectroscopy. These goals are achievable based on our extensive previous related multidisciplinary knowledge with thin film heterostructure properties using state of the art molecular beam epitaxial system for film growth and measurement facilities, including atomic level characterization of interfaces utilizing the national facilities. Education and training of students (including high school students summer programs) and young scientists in the areas dictated quantum coherent topology driven phenomena are planned under this program.