Novel Electron Fluids in Quantum Materials

量子材料中的新型电子流体

• 批准号: EP/T001194/1
• 负责人: Andrei Shytov
• 金额: $ 44.36万
• 依托单位: UNIVERSITY OF EXETER
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FT001194%2F1
• 关键词: Novel; Electron; Fluids; Quantum; Materials

The discovery of graphene and other atomically thin quantum materials has defined a new paradigm in nanoscience. Electrons in these materials behave as light shining through window glass, propagating ballistically, unimpeded by disorder and defects. This leads to record-high electric conduction and other unique properties, which enable new directions for device engineering and have the potential to radically transform the performance of electronic devices. Remarkably, the quantum phenomena underlying these excellent electronic properties persist even at room temperature, changing the rules for signal processing and opening new avenues for quantum electronics and calling for innovative approaches to nanoelectronics that exploit new physical ideas rather than the conventional schemes. Electron fluid (e-fluid) is a new state of matter that may help to address this challenge. In e-fluids, the flow of electric charge mimics that of viscous fluids, such as water, honey, or air, in a radical departure from textbook Ohm's law seen in conventional metals and semiconductors. In 20th century, viscous fluids were employed to engineer fluidic circuits and even simple but fully functional hydraulic computers operating at low frequencies. (For example, such devices found their use in automatic transmissions systems in vehicles.) E-fluids in quantum materials, in particular graphene, a one-atom-thin layer of carbon, move much faster and on much shorter scales. Extending fluidic designs to e-fluids will lead to logic gates and integrated circuits that operate a billion times faster, and are 10000 times smaller. Can the performance of fluidic circuits surpass that of conventional semiconductor transistors?We believe that the answer to this question is in the affirmative: fluidic circuit components employing e-fluids in novel materials may operate faster, on a smaller scale, and provide novel functionalities. E-fluids will enable ultrafast low-power transistors, low-resistivity interconnects, and direct-current transformers. The fluidic architectures will provide support to modern technologies such as machine learning through achieving energy-efficient operation of analogue nanoscale devices at ultrahigh frequencies. To put these ideas on a firm ground and to unleash the potential of e-fluidics, a deeper understanding of the physics of e-fluids must be developed. This project is a condensed-matter theorist's answer to the demands of nanoscale electronics. In the PI's preliminary work, an interesting and potentially useful regime, the onset of fluidity was identified. We shall focus our efforts on the onset of fluidity, describing it via mathematical models, and employing these to suggest design ideas for applications in nanoscale electronics. The onset of fluidity occurs when the frequency of collisions between charge carriers reaches a certain threshold such that a current flow can drag ambient particles. In this regime, nonlocal effects and nonlinear couplings between currents are expected to be maximal. The latter is very beneficial for potential applications: electric current can be employed to manipulate the flow of another current. More detailed recent analysis demonstrate that the onset is not just a threshold for fluid-mechanical behaviour but an entirely new regime, in which injected currents propagate through the fluid via directed jets comprised of electrons and holes. We will study theoretically the key phenomena occurring at the fluidity onset in graphene: charge flows, formation of jets, nonlinear coupling between the currents, energy transport, sensitivity to external magnetic field, response to fast electric fields. The research will be linked to experimental efforts done by project partners. The insights into the physics of fluidity will eventually help, via interaction with other teams, to propose novel designs of elements of nanoelectronic circuits based on the principles of e-fluidics.

石墨烯和其他原子级薄量子材料的发现定义了纳米科学的新范式。这些材料中的电子表现为透过窗户玻璃的光，弹道传播，不受无序和缺陷的阻碍。这导致了创纪录的高电导率和其他独特性能，为器件工程提供了新的方向，并有可能从根本上改变电子器件的性能。值得注意的是，这些优异的电子特性背后的量子现象即使在室温下也持续存在，改变了信号处理的规则，为量子电子学开辟了新的途径，并呼吁采用新的物理思想而不是传统方案的创新方法来研究纳米电子学。电子流体（e-fluid）是一种新的物质状态，可能有助于应对这一挑战。在电子流体中，电荷的流动模仿粘性流体，如水，蜂蜜或空气，与传统金属和半导体中的教科书欧姆定律完全不同。在20世纪，粘性流体被用于设计流体回路，甚至是简单但功能齐全的低频液压计算机。(For例如，这种装置可用于车辆的自动变速器系统中。量子材料中的电子流体，特别是石墨烯，一个原子薄的碳层，移动得更快，尺度更短。将流体设计扩展到电子流体将导致逻辑门和集成电路的运行速度提高10亿倍，体积缩小10000倍。射流电路的性能能否超过传统的半导体晶体管？我们相信这个问题的答案是肯定的：采用新型材料的电子流体的流体回路组件可以更快地操作，更小的规模，并提供新的功能。电子流体将使超快低功率晶体管，低电阻率互连和直流变压器成为可能。流体架构将为现代技术提供支持，例如机器学习，通过实现模拟纳米级设备在100MHz下的节能操作。为了把这些想法放在坚实的基础上，并释放电子流体的潜力，必须对电子流体的物理学有更深入的了解。这个项目是凝聚态理论家对纳米级电子学需求的回答。在PI的初步工作，一个有趣的和潜在的有用的制度，流动性的发病被确定。我们将集中精力在流动性的开始，通过数学模型描述它，并利用这些建议在纳米级电子应用的设计思路。当电荷载流子之间的碰撞频率达到一定阈值时，流动性开始发生，使得电流可以拖动周围的颗粒。在这种情况下，电流之间的非局部效应和非线性耦合预计将是最大的。后者对于潜在的应用是非常有益的：电流可以用来操纵另一个电流的流动。更详细的最近的分析表明，发病不仅是流体力学行为的阈值，但一个全新的制度，其中注入的电流通过由电子和空穴组成的定向射流传播通过流体。我们将从理论上研究石墨烯中流动性开始时发生的关键现象：电荷流动，射流的形成，电流之间的非线性耦合，能量传输，对外部磁场的敏感性，对快速电场的响应。该研究将与项目合作伙伴所做的实验工作联系起来。通过与其他团队的互动，对流动性物理学的见解最终将有助于提出基于电子流体原理的纳米电子电路元件的新颖设计。