Superconducting and Metal-Insulator Transitions in Quasi-Two-Dimensional Strongly Correlated Materials

非技术性：许多具有潜在重大技术重要性的新材料的电子特性由电荷载流子之间的相互作用主导。 这些相关性引起了各种现象，包括新的物质状态的出现和不同相之间的转变，例如金属到绝缘体或超导体到正常状态。 然而，这些转变的微观机制和在这种强相关系统中的各个阶段的性质还没有很好地理解。 这项研究解决了有关超导和金属-绝缘体转变的基本问题，在两类分层的，强相关的材料，氧化铜高温超导体和一系列新的有机系统，通过在宽范围的温度和磁场进行电荷传输的测量。 该项目的结果对于理解强相关材料至关重要，这将通过最终影响科学和技术的发展而造福社会。 该项目的一个关键组成部分是对研究生进行教育和培训，以便将来在学术界、国家实验室和工业界就业。 它还包括各种活动，以扩大在科学，技术，工程和数学领域的代表性不足的群体的参与，与公众的联系，以及对研究基础设施的影响。技术：该项目解决了强关联材料物理学中的几个基本问题，如非常规超导性和准二维系统中的莫特金属-绝缘体转变。 由于反常输运性质是强关联材料的关键特性之一，因此实验涉及电输运，包括时间分辨协议。 研究集中在两类准二维体系，铜酸盐和新合成的取代系列准二维有机物。 在这两种情况下，非常规超导性的出现是由于通过改变掺杂或化学压力分别调整莫特转变的结果。 在铜氧化物中，目标是探测高磁场对超导性的破坏，并澄清自旋和电荷有序，无序和量子相位波动各自的作用，作为掺杂的函数。 在有机物中，重点是通过探索热和磁场调谐的超导转变来理解非常规的超导性。此外，莫特金属-绝缘体转变和自旋液体激发的作用进行了探讨，使用时间分辨技术。 从该项目中获得的知识对于凝聚态物理学的进一步发展至关重要。该奖项反映了NSF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。

NONTECHNICAL:Electronic properties of many new materials with potentially great technological importance are dominated by interactions among charge carriers. Those correlations give rise to a variety of phenomena, including the emergence of novel states of matter and transitions between different phases, such as metal to insulator or superconductor to normal. However, microscopic mechanisms underlying these transitions and the nature of various phases in such strongly correlated systems are not well understood. This research addresses fundamental questions about superconducting and metal-insulator transitions in two classes of layered, strongly correlated materials, copper-oxide high-temperature superconductors and a new series of organic systems, by performing measurements of charge transport over a wide range of temperatures and magnetic fields. The results of this project are crucial for understanding of strongly correlated materials, which will benefit society by ultimately influencing the development of science and technology. A key component of the project is education and training of graduate students for future careers in academia, national laboratories, and industry. It also incorporates various activities to broaden the participation of underrepresented groups in the areas of science, technology, engineering, and mathematics, outreach to general public, and impact on research infrastructure.TECHNICAL:This project addresses several fundamental questions in the physics of strongly correlated materials, such as unconventional superconductivity and the Mott metal-insulator transition in quasi-two-dimensional systems. Since anomalous transport properties are one of the key characteristics of strongly correlated materials, experiments involve electrical transport, including time-resolved protocols. Studies focus on two classes of quasi-two-dimensional systems, cuprates and newly synthesized substitutional series of quasi-two-dimensional organics. In both cases, unconventional superconductivity emerges as a result of tuning through the Mott transition by varying doping or chemical pressure, respectively. In cuprates, the goal is to probe the destruction of superconductivity by high magnetic fields and to clarify the respective roles of spin and charge orders, disorder, and quantum phase fluctuations, as a function of doping. In organics, the focus is on understanding unconventional superconductivity by exploring both thermal and magnetic-field-tuned superconducting transitions. In addition, the Mott metal-insulator transition and the role of spin liquid excitations are probed using time-resolved techniques. The knowledge gained from this project is essential for further development of condensed matter physics.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.