Materials World Network: Properties of Electrostatically Doped Oxide Superconductors

材料世界网：静电掺杂氧化物超导体的特性

• 批准号: 1209578
• 负责人: Allen Goldman
• 金额: $ 48万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1209578&HistoricalAwards=false
• 关键词: Materials; World; Network; Properties; Electrostatically

TECHNICAL SUMMARY:This Materials World Network project will synthesize, characterize and study experimentally, properties of high temperature superconductors such as the cuprates, whose carrier concentrations will be electrostatic altered in field effect transistor geometries employing an electronic double layer transistor (EDLT) technique that uses ionic liquids as gate dielectrics. In effect electrostatic doping would replace chemical doping. Since carrier concentration is a control parameter that governs the properties of these systems, this approach will facilitate the investigation of systems through continuous and reversible changes of carrier concentration. The program includes studies of X-ray scattering and superfluid density to supplement the usual measurements of electrical transport and magneto-transport. Electronic double layer transistors contain a gate electrode, a layer into which charge can be accumulated or depleted, source and drain electrodes, as well as electrodes for measuring longitudinal and transverse voltages. Ionic liquids are molten salts consisting of large ions such that their Coulomb interaction is sufficiently small to make them room temperature liquids. Upon applying a gate voltage, ions move to the surface of the layer to be doped, forming an electric double layer such that with the charge induced, acts as a capacitor of nanoscale thickness. The charge accumulation or depletion layers formed using EDLTs may be the order of just a few unit cells in thickness and will contain high electric fields and electric field gradients. The doped layer may be a two-dimensional rather than a three-dimensional superconductor. It is thus not a given that electrostatic doping is completely equivalent to chemical doping to the same charge level. On the other hand, when the microscopic process of electric field doping becomes well understood, considerable insight into the rich physics of the cuprates may be gained. NON-TECHNICAL SUMMARYThis Materials World Network project will employ ionic liquid field effect transistor configurations to electrostatically alter charge carrier densities, and study the resultant changes in the physical properties of high temperature superconductors. The usual approach to this is to prepare samples with different chemical compositions. This new approach eliminates the need to do this, speeding the rate of exploration. Ionic liquids, which are molten salts at room temperature, replace the gate insulator in the field effect transistor configuration. Their use can facilitate charge transfers more than 100 times greater than achievable with conventional insulators, because of the formation of an electronic double layer, which is in effect a capacitor with a nanometer scale gap. The broader impacts of the proposed program include training of graduate students in a traditional physics Ph.D. program and providing a venue for useful and positive research experiences for undergraduates from both Minnesota and elsewhere. In addition, this international effort will allow for strong interaction of personnel from the US and Spain, which will broaden the experience of young scientists in the global scientific community. Finally, the work described in this proposal may have an impact on the search for new superconductors, which is one of the grand challenges of contemporary condensed matter and materials physics. It could demonstrate that electrostatic doping is a viable alternative to traditional chemical doping in this quest. This project is supported by the Condensed Matter Physics program and the Office of Special Programs, Division of Materials Research.

技术摘要：该材料世界网络项目将合成，表征和实验研究高温超导体的特性，如铜酸盐，其载流子浓度将在场效应晶体管几何形状中采用电子双层晶体管（EDLT）技术进行静电改变，该技术使用离子液体作为栅极电荷。实际上，静电掺杂将取代化学掺杂。 由于载流子浓度是一个控制参数，管理这些系统的性能，这种方法将有利于通过连续和可逆的载流子浓度变化的系统的调查。 该计划包括X射线散射和超流体密度的研究，以补充电输运和磁输运的通常测量。 电子双层晶体管包含栅电极、电荷可以在其中积累或耗尽的层、源电极和漏电极以及用于测量纵向和横向电压的电极。离子液体是由大离子组成的熔融盐，使得它们的库仑相互作用足够小以使它们成为室温液体。在施加栅极电压时，离子移动到待掺杂的层的表面，从而形成双电层，使得在感应电荷的情况下充当纳米级厚度的电容器。使用EDLT形成的电荷累积或耗尽层在厚度上可以是仅几个单位单元的数量级，并且将包含高电场和电场梯度。 掺杂层可以是二维的而不是三维的超导体。 因此，静电掺杂完全等同于化学掺杂到相同的电荷水平并不是一个给定的。 另一方面，当电场掺杂的微观过程变得很好理解时，可以获得对铜酸盐丰富物理学的相当深入的了解。非技术总结这个材料世界网络项目将采用离子液体场效应晶体管配置来静电改变电荷载流子密度，并研究高温超导体物理特性的变化。通常的方法是制备具有不同化学成分的样品。 这种新方法消除了这样做的必要性，加快了探索的速度。在室温下为熔融盐的离子液体替代场效应晶体管配置中的栅极绝缘体。它们的使用可以促进电荷转移比传统绝缘体所能实现的高100倍以上，因为形成了电子双层，这实际上是具有纳米级间隙的电容器。 拟议的计划的更广泛的影响，包括在传统的物理博士研究生的培训。计划，并提供一个场地，为来自明尼苏达州和其他地方的本科生有用和积极的研究经验。此外，这一国际努力将使美国和西班牙的人员能够进行强有力的互动，这将扩大全球科学界年轻科学家的经验。 最后，本提案中描述的工作可能会对寻找新的超导体产生影响，这是当代凝聚态物质和材料物理学的重大挑战之一。 它可以证明，静电掺杂是一个可行的替代传统的化学掺杂在这方面的追求。 该项目由凝聚态物理计划和材料研究部特别计划办公室支持。