Understanding the Hinge Modes in a Topological Superconductor

摘要：近年来，人们预测了一种新的物质相，称为高阶拓扑态。这种状态在晶体不同表面的交叉处包含特定的新模式。这些所谓的“铰链”或“角落”模式有可能成为未来拓扑量子计算机的基础，不受错误的影响，能够执行目前无法想象的计算。这种材料的一个令人兴奋的例子是feese， PI提供了它是高阶拓扑超导体的第一个证据。利用制造，电学和光谱学方面的专业知识，PI将开发新的方法来系统地探测feese中铰链模式的特性。这些主题和技巧也为创建公开演讲和招募各种各样的学员（本科生和研究生）提供了一个很好的起点，他们也参与了公共宣传。该项目的参与者获得宝贵的专业技能：协作、计算、制造和表征。技术摘要：近年来出现了高阶拓扑相，其二维或多维边界模式小于体。这些系统的边界状态本身是拓扑的，有不同的符号。利用他在制造，电学和光谱学方面的专业知识，PI将开发新的方法来探测feese中铰链模式的特性。一系列接触配置和协议将确定将铰链与本体隔离的最佳方法。这项工作是通过光热测量来辅助铰链成像的。仔细研究磁场和磁接触的影响将决定自旋动量锁定的细节。这些研究将揭示铰链模式的输运、热和自旋动量锁定。因此，它们的鲁棒性将被直接探测，同时确定适当的基态哈密顿量来描述铰链。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-Technical Abstract:In recent years a new kind of phase of matter has been predicted, called a Higher Order topological state. This state contains specific new modes on intersections of different surfaces of the crystal. These so-called "hinge" or "corner" modes have the potential to form the basis of future topological quantum computers, immune to errors and able to perform calculations currently unthinkable. An exciting example of such materials is FeTeSe, where the PI provided the first evidence that it is a higher order topological superconductor. Using expertise in fabrication, electrical, and optical spectroscopy, the PI will develop new means to probe the properties of the hinge modes in FeTeSe systematically. The topics and techniques also provide an excellent starting point for creating public talks and recruiting a diverse set of trainees, undergraduate and graduate students, who also participate in public outreach. The project's participants gain valuable professional skills in: collaboration, computation, fabrication, and characterization. Technical Abstract:Higher order topological phases have recently emerged, with boundary modes in two or more dimensions smaller than the bulk. These are systems whose boundary states are themselves topological, gapped with different signs. Using his expertise in fabrication, electrical, and optical spectroscopy, the PI will develop new means to probe the properties of the hinge modes in FeTeSe. An array of contact configurations and protocols will determine the best method to isolate the hinge from the bulk. This effort is aided by photothermal measurements to image the hinges. Careful studies of the effects of magnetic fields and magnetic contacts will determine the details of spin momentum locking. The studies will reveal the transport, thermal, and spin-momentum locking of the hinge modes. As such, their robustness will be directly probed, along with determining the proper ground-state Hamiltonian to describe the hinges.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.