Exploring tunable magnet/superconductor hybrid quantum systems via scanning tunneling microscopy

通过扫描隧道显微镜探索可调磁体/超导体混合量子系统

• 批准号: 459025680
• 负责人: Dr. Roberto Lo Conte, Ph.D.
• 金额: --
• 依托单位: Institut für Nanostruktur- und Festkörperphysik (INF)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2021
• 资助国家: 德国
• 起止时间: 2020-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/459025680?language=en
• 关键词: Exploring; tunable; magnet; superconductor; hybrid

In recent years the investigation of quantum materials has been experiencing an unprecedented acceleration, mostly due to the promise of applications in the upcoming quantum information technologies. Magnet/superconductor hybrid (MSH) systems are very promising candidates for designing new quantum materials with tunable properties. Rich new physics is expected to emerge at the interface between a superconducting substrate and an ultrathin magnetic layer hosting non-collinear spin-textures. On the one hand, the superconducting state of the substrate is expected to influence the magnetic phase established in the ultrathin magnet. On the other hand, topologically protected electronic states are predicted to be present at the hetero-interface due to the interplay between the non-collinear spin-texture and the superconducting phase, allowing for the emergence of topological superconductivity.This project focuses on the investigation of new MSH quantum systems via spin-polarized scanning tunnelling microscopy (SP-STM). The atomic spin texture in the deposited magnetic layers will be imaged as a function of temperature and magnetic fields, allowing to understand the influence of superconductivity on the magnetic phase established in the ultra-thin film. In addition, scanning tunnelling spectroscopy (STS) will be used to investigate the electronic properties of the hybrid system and to unveil the emergence of topological superconductivity. The electronic properties will be characterized at the location of physical (edges of nanostructures) as well as magnetic (domain walls) boundaries, in the attempt to distinguish among the different possible origins of topological electronic states. This kind of investigation will be done on two different types of MSH systems. The initial study will be conducted on materials systems consisting of a bulk superconductor with on top magnetic monolayers and double-layers. Subsequently, the study will move towards slightly more complex systems, where a very thin interlayer of a second superconducting material will be inserted at the interface of the initial magnet/superconductor system. The aim is to understand how the properties of the initial MSH system can be tuned by the presence of a second superconducting material via proximity effects. What will be the superconducting transition temperature of the whole system? Can the transition temperature and so the quantum properties of the trilayer be tuned by changing the thickness of the superconducting interlayer? How does the spin-texture change as a function of the material and the thickness of the interlayer? Can different topological superconducting states be stabilized by changing the interlayer? These are some of the key scientific questions that this research project will try to answer.

近年来，量子材料的研究经历了前所未有的加速，这主要是由于即将到来的量子信息技术的应用前景。磁体/超导体混合（MSH）系统是设计具有可调特性的新型量子材料的非常有前途的候选者。丰富的新物理学预计将出现在超导基底和具有非共线自旋纹理的超薄磁性层之间的界面处。一方面，基底的超导状态预计会影响超薄磁体中建立的磁相。另一方面，由于非共线自旋结构和超导相之间的相互作用，预计拓扑保护的电子态将出现在异质界面上，从而出现拓扑超导性。该项目重点研究通过自旋偏振扫描隧道显微镜 (SP-STM) 开发新的 MSH 量子系统。沉积磁性层中的原子自旋纹理将被成像为温度和磁场的函数，从而可以了解超导性对超薄膜中建立的磁性相的影响。此外，扫描隧道光谱（STS）将用于研究混合系统的电子特性并揭示拓扑超导的出现。电子特性将在物理（纳米结构的边缘）和磁性（畴壁）边界的位置进行表征，试图区分拓扑电子态的不同可能起源。这种调查将在两种不同类型的 MSH 系统上进行。初步研究将针对由带有顶部磁性单层和双层的体超导体组成的材料系统进行。随后，研究将转向稍微复杂的系统，在初始磁体/超导体系统的界面处插入非常薄的第二种超导材料夹层。目的是了解如何通过邻近效应通过第二种超导材料的存在来调整初始 MSH 系统的特性。整个系统的超导转变温度是多少？能否通过改变超导中间层的厚度来调节三层结构的转变温度和量子特性？自旋纹理如何随着材料和中间层厚度的变化而变化？不同的拓扑超导态能否通过改变夹层来稳定？这些是该研究项目将试图回答的一些关键科学问题。