Theoretical Topics in Superconductivity and Graphene

超导和石墨烯的理论主题

• 批准号: 3418-2013
• 负责人: Carbotte, Jules
• 金额: $ 2.4万
• 依托单位: McMaster University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=544105
• 关键词: Theoretical; Topics; Superconductivity; Graphene

Superconductors are metals which carry a current without dissipation. This is a very desirable property for making large electromagnets used in medical imaging. But such magnets presently work only at low temperatures. Hence they require refrigeration. So finding materials suitable for the fabrication of magnets that would operate at room temperature is very important. New classes of superconductors are discovered every few years. An important class is the cuprates which are the materials that hold the record critical temperature value [Tc] up to about 150 Kelvin. More recently Fe-based metals have also been found to superconduct and we wish to study their properties with a view at increasing the value of Tc. Superconductors are not the only metals of importance in technological applications. The electronic industry can also benefit from new semiconducting materials. In 2004, a single sheet of graphite was exfoliated which is a membrane a single atom thick and has amazing unexpected properties. As an example, the motion of the charge carriers in graphene is governed by a relativistic Dirac equation. Their mobility is excellent and many novel applications have been suggested such as elements in display screens. We are studying the properties of graphene under magnetic field and how its properties depend on the coulomb interactions between the electrons. This is important in understanding the interaction of light with the charge oscillations in the graphene sheets. There are also other new materials with different and quite new functionalities. These include a single layer MoS2 which is a direct gap semiconductor with two valleys. It is possible in these materials to excite electrons exclusively from one of the two valleys leaving the others unaffected. This could be very useful in applications to the communication industry .We plan to study their optical properties with an aim at understanding how incident light can be change to a charge current in these systems. All the proposed research involves theoretical studies aimed at better microscopic understanding of the properties of recently discovered materials.

超导体是载流而不耗散的金属。这是制造用于医学成像的大型电磁铁的非常理想的特性。但这种磁体目前只能在低温下工作。因此，它们需要冷藏。因此，寻找适合于制造在室温下工作的磁体的材料是非常重要的。每隔几年就会有新的超导体被发现。一个重要的类别是铜酸盐，它是将记录的临界温度值[TC]保持到约150开尔文的材料。最近，铁基金属也被发现具有超导性，我们希望研究它们的性质，以期提高T_c的值。在技术应用中，超导体并不是唯一重要的金属。电子行业也可以从新的半导体材料中受益。2004年，一片石墨被剥离，这是一个单原子厚度的膜，具有令人惊讶的意想不到的特性。例如，石墨烯中载流子的运动受相对论狄拉克方程的支配。它们的移动性很好，已经提出了许多新的应用，例如在显示屏上的元件。我们正在研究磁场下石墨烯的性质，以及它的性质如何依赖于电子之间的库仑相互作用。这对于理解光与石墨烯薄片中的电荷振荡的相互作用是重要的。还有其他具有不同和相当新功能的新材料。其中包括单层MoS2，这是一种具有两个山谷的直接带隙半导体。在这些材料中，有可能只从两个山谷中的一个激发电子，而不影响其他山谷。这在通信行业的应用中可能非常有用。我们计划研究它们的光学性质，目的是了解入射光如何在这些系统中转变为电荷电流。所有拟议的研究都涉及理论研究，目的是更好地从微观上了解最近发现的材料的性质。