Simulations of Competing Phases and Quantum Criticality in Strongly Correlated Materials

非技术性总结材料研究部资助该奖项，支持新形式主义，算法和代码的发展，以及它们在材料中组成电子的复杂行为研究中的应用的研究和教育。材料科学最迷人的领域之一是研究电子如何在材料中组织，产生不同的量子相，如金属，绝缘体，半导体或超导体，其特征在于不同的和技术上重要的属性。当多个这样的相共存并在材料中竞争时，就会发生量子临界。在这些相之间的边界，可能不存在已确定的相;因此，可能会出现全新的物质状态。这些新的相和它们的竞争不仅从基本的角度来看是迷人的，而且还可能拥有新的应用和功能的希望，因为在相之间的脆弱平衡，电场或磁场，或压力的应用，或材料化学成分的变化可能会显着改变其特性。然后，随着系统在不同状态之间“切换”，新的功能可能会出现。该项目需要开发相关的方法，并将使用超级计算机来研究这些物质的量子临界态，不同阶段之间的竞争，以及它们对不同外部场的反应。该研究将与印度的研究人员合作进行，进一步加强了由几名现任和前任学生组成的国际合作。该项目还将涉及一些推广工作，以提高学生对科学的兴趣和成就，并鼓励学生考虑STEM职业。该奖项资助的研究人员将参加每年夏天的Beowulf训练营，高中生将在那里构建和使用一台小型超级计算机。技术总结材料研究部资助该奖项，支持相关电子材料中复杂行为的研究和教育，包括铜酸盐超导体中的竞争相，重费米子系统，无序相互作用电子系统和超导体。本项目的重点将放在识别和研究新的量子临界点和竞争相，以及安德森无序驱动的量子相变及其与相互作用的竞争。本项目的目标是继续开发新的形式化、算法和代码，并将其用于相关电子材料中复杂行为的研究。该研究小组将专注于量子临界性和局部化附近的无序相互作用模型的模拟。量子临界性是非常重要的，因为相关的跃迁是由量子而不是热涨落驱动的。PI和他的团队将更好地理解相关和强无序系统中的竞争相，这可能导致新的功能，包括安德森金属-绝缘体转变和其他量子相变。对量子临界性的更全面理解可能反过来导致对高温超导体和其他技术上重要的材料的更好理解。该项目将采用一系列理论/计算工具，包括多尺度方法，量子蒙特卡罗和快速近似簇解算器，和新的方法来处理无序相互作用系统附近的安德森本地化转变，包括最近开发的典型的-用于研究安德森局域化量子相变的中等动力学团簇近似。这项研究将与印度的研究人员合作进行，进一步加强了包括几名现任和前任学生在内的既定国际合作。该项目还将涉及一些推广工作，以提高学生对科学的兴趣和成就，并鼓励学生考虑STEM职业。由该奖项资助的研究人员将参加每年夏天的Beowulf Bootcamp，高中生将在那里建造和使用一台小型超级计算机。

NONTECHNICAL SUMMARYThe Division of Materials Research funds this award that supports research and education on the development of new formalisms, algorithms and codes, and on their use in the study of complex behavior of constituent electrons in materials.One of the most fascinating areas of materials science is the study of how electrons organize in materials, giving rise to different quantum phases, such as metals, insulators, semiconductors or superconductors, which are characterized by different and technologically important properties. Quantum criticality occurs when multiple such phases coexist and compete in a material. At the boundaries between these phases, it is possible that no well-established phase exists; as a result, completely new states of matter may emerge. These new phases and their competition is not only fascinating from a fundamental standpoint, but may also hold the promise of new applications and functionalities since at a tenuous balance between phases, the application of an electric or magnetic field, or pressure, or changes in the chemical composition of the material may dramatically change its properties. New functionalities may then emerge as the system "switches" between the different states. The project entails developing relevant methodology, and will use supercomputers to study these quantum critical states of matter, the competition between different phases, and their response to different external fields.The research will be carried out in collaboration with researchers in India, furthering an established international collaboration involving several present and former students. The project will also involve a number of outreach efforts developed to increase student interest and achievement in the sciences, and to encourage students to consider STEM careers. The researchers funded by the award will participate in a Beowulf Bootcamp each summer where high-school students will construct and use a small supercomputer.TECHNICAL SUMMARYThe Division of Materials Research funds this award that supports research and education on complex behaviors in correlated electronic materials, including competing phases in cuprate superconductors, heavy-Fermion systems, and disordered interacting electronic systems and superconductors. Special emphasis will be placed on identifying and studying new quantum critical points and competing phases, and the Anderson disorder-driven quantum phase transition and its competition with interactions.The goal of this project is to continue the development of new formalisms, algorithms and codes, and to use them in the study complex behavior in correlated electronic materials. The research team will focus on simulations of quantum criticality and disordered interacting models near localization. Quantum criticality is of great fundamental interest, since the associated transitions are driven by quantum rather than thermal fluctuations. The PI and his group will develop a better understanding of the competing phases in correlated and strongly disordered systems that could lead to new functionalities, including the Anderson metal-insulator transition, and other quantum phase transitions. A more complete understanding of quantum criticality may in turn lead to a better understanding of high-temperature superconductors and other technologically important materials.The project will employ an array of theoretical/computational tools including multiscale approaches, quantum Monte Carlo, and fast approximate cluster solvers, and novel methods to treat disordered interacting systems near an Anderson localization transition including the recently developed typical-medium dynamical cluster approximation used to study the Anderson localization quantum phase transition.The research will be carried out in collaboration with researchers in India, furthering an established international collaboration involving several present and former students. The project will also involve a number of outreach efforts developed to increase student interest and achievement in the sciences, and to encourage students to consider STEM careers. The researchers funded by the award will participate in a Beowulf Bootcamp each summer where high-school students will construct and use a small supercomputer.