Magnetism at low dimensions is a thriving field of research with exciting opportunities in technology. This Colloquium focuses on the properties of 1D magnetic systems on solid surfaces. From the emulation of 1D quantum phases to the potential realization of Majorana edge states, spin chains are unique systems to study. The advent of scanning tunneling microscope (STM) based techniques has permitted us to engineer spin chains in an atom-by-atom fashion via atom manipulation and to access their spin states on the ultimate atomic scale. Here the current state of research on spin correlations and dynamics of atomic spin chains as studied by the STM is presented. After a brief review of the main properties of spin chains on solid surfaces, spin chains are classified according to the coupling of their magnetic moments with the holding substrate. This classification scheme takes into account that the nature and lifetimes of the spin-chain excitations intrinsically depend on the holding substrate. Interest is shown of using insulating layers on metals, which generally results in an increase in the spin state’s lifetimes such that their quantized nature gets evident and they are individually accessible. Next shown is the use of semiconductor substrates promising additional control through the tunable electron density via doping. When the coupling to the substrate is increased for spin chains on metals, the substrate conduction electron mediated interactions can lead to emergent exotic phases of the coupled spin chain-substrate conduction electron system. A particularly interesting example is furnished by superconductors. Magnetic impurities induce states in the superconducting gap. Because of the extended nature of the spin chain, the in-gap states develop into bands that can lead to the emergence of 1D topological superconductivity and consequently to the appearance of Majorana edge states. Finally, an outlook is given on the use of spin chains in spintronics, quantum communication, quantum computing, quantum simulations, and quantum sensors.

中文翻译：

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座谈会：表面上的原子自旋链

低尺寸的磁性是一个蓬勃发展的研究领域，具有令人兴奋的技术机遇。这次专题讨论会着重于固体表面上的一维磁性系统的特性。从一维量子相的仿真到马约拉那边沿状态的潜在实现，自旋链是需要研究的独特系统。基于扫描隧道显微镜（STM）的技术的出现使我们能够通过原子操纵以原子接原子的方式设计自旋链，并在最终原子尺度上访问其自旋态。此处介绍了STM研究的原子自旋链的自旋相关性和动力学的研究现状。在简要回顾了固态表面上自旋链的主要特性之后，根据自旋链的磁矩与固定基底的耦合对自旋链进行了分类。该分类方案考虑到自旋链激发的性质和寿命本质上取决于保持基质。显示出在金属上使用绝缘层的兴​​趣，这通常会导致自旋状态的寿命增加，从而使它们的量化性质变得明显并且可以单独访问。接下来显示的是半导体衬底的使用，有望通过掺杂通过可调电子密度实现额外控制。当金属上的自旋链增加与基底的偶联时，基底传导电子介导的相互作用会导致偶联的自旋链-基底传导电子系统出现异质相。超导体提供了一个特别有趣的示例。磁性杂质会在超导间隙中感应出态。由于自旋链的延伸性质，能隙内状态发展为能导致一维拓扑超导出现并由此导致马约拉纳边沿状态出现的能带。最后，展望了自旋电子学中自旋链的使用，量子通信，量子计算，量子模拟和量子传感器。