Superconductor-(Metal)-Insulator Transitions: Understanding the Emergence of Metallic States, A Continuation Proposal

超导体-（金属）-绝缘体转变：了解金属态的出现，延续提案

• 批准号: 2307132
• 负责人: Aharon Kapitulnik
• 金额: $ 72.76万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-01 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2307132&HistoricalAwards=false
• 关键词: Superconductor; Metal; Insulator; Transitions; Understanding

Nontechnical Abstract: An increasing number of recent experiments reveal a possible “anomalous metallic state” (AMS), which exhibits properties that cannot be understood on the basis of “standard paradigms” of electrons in solid-state systems. The project aims to explore the extent of the emergence of the anomalous metallic phase and its relation to a failed superconducting and/or insulating states. Furthermore, the project explores possible variants of the AMS in multiple cases. Results are expected to shed light on a new class of metallic states of matter and will have an impact on physics as a discipline, on education and on society. Pointing to a lack of full understanding of one of the fundamental types of substances in nature, it ought to trigger curiosity at all levels of society, thus helping to enhance our scientific understanding and possible impact technological applications.Technical Abstract: An increasing number of recent experiments on disordered superconducting films, initially searching for a superconductor-insulator transition (SIT), have been pointing to the possibility of a zero-temperature transition from a superconductor to an “anomalous metallic state” (AMS) that features properties of a “failed superconductor.” This state exhibits significant superconducting correlations, yet the system fails to globally condense even at zero temperature, settling at a finite conductivity through a quantum superconductor to metal transition (QSMT). Furthermore, where strongly inhomogeneous systems are studied, charging energy of the superconducting islands, which typically leads to an insulating state through Coulomb blockade, can experience charge fluctuations when weakened, preventing the establishment of a true insulator. As observation of deviations from the “standard paradigm,” particularly in the limit of two-dimensions, have been fast accumulating, it becomes clear that there exists a new class of metallic states as the temperature tends to zero, where the electronic properties cannot remotely be understood on the basis of Fermi liquid and Drude theories, thus pointing to a new paradigm for metallic states in nature. Exploring SIT and the emergence of anomalous metallic states and their properties are the focus of this projects. This is achieved through focus on enhanced phase fluctuations materials either using highly granular films or unconventional superconductors such as superconductor/ferromagnet bilayers, as well as low-temperature magneto-transport measurements including sensitivity to external perturbations and improved mutual-inductance probe for the study of superfluid response.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.

非技术摘要：越来越多的最新实验揭示了可能的“异常金属状态”（AMS），该实验表现出基于固态系统中电子的“标准范式”无法理解的属性。该项目旨在探索异常金属阶段的出现及其与失败的超导和/或绝缘状态的关系。此外，该项目在多种情况下探讨了AM的可能变体。预计结果将阐明一类新的物质金属状态，并将对物理学，学科，教育和社会产生影响。 Pointing to a lack of full understanding of one of the fundamental types of substances in nature, it ought to trigger curiosity at all levels of society, thus helping to enhance our scientific understanding and possible impact technical applications.Technical Abstract: An increasing number of recent experiments on disordered superconducting films, initially searching for a superconductor-insulator transition (SIT), have been pointing to the possibility of a zero-temperature transition从超导体到“异常金属状态”（AMS），具有“失败超导体”的特性。该状态表现出明显的超导体相关性，但是即使在零温度下，系统也无法在全球固定，通过量子超导体到金属过渡（QSMT）以有限的电导率沉降。此外，在强烈不均匀的系统进行研究的地方，充电超导岛的能量通常会通过库仑阻断导致绝缘状态，在削弱时会经历电荷波动，从而阻止建立真正的绝缘体。随着对“标准范式”的偏离观察，特别是在二维限制的情况下，已经快速积累，很明显，由于温度趋于零，因此存在一类新的金属状态，在这种情况下，在Fermi液体液体和DRUDE理论的基础上无法理解电子特性，从而指向新的范式，以实现新的范围。探索SIT和异常金属状态及其特性的出现是该项目的重点。这是通过专注于使用高度颗粒状膜或非常规的超导体（例如超导/铁磁双层）以及低温的磁力传输测量值（包括对外部效果和改进的共同感应响应的敏感性）的敏感性，以实现超级态度的敏感性，从而响应了超级感应，以实现超级响应的敏感性。使用基金会的智力优点和更广泛的影响标准，认为通过评估被认为是宝贵的支持。