Experimental Studies of Organic Crystals, Metals and Superconductors

9976576 Chaikin这个项目使用磁场，低温，不寻常的材料和新颖的光刻相结合，以测试凝聚态物理学的一些基本思想。Bechgaard盐（TMTSF）2 X（X= PF_6、ClO_4等）是高度各向异性的电子导体，它表现出许多自然界中最有趣的基态：金属，超导，自旋密度波和量子霍尔效应。此外，它们在磁场中表现出独特的性质，其中磁场长度与费米波矢竞争，产生级联的相变。这些可重复性效应也存在于磁通量子化实验中，这些实验是在微米长度尺度上对图案化超导网络进行的，与相干长度相当。当在纳米长度尺度上图案化时，在半导体和金属中可能发生类似的相干干涉效应。我们使用二嵌段共聚物作为光刻掩模，在这种长度尺度上制造图案，为器件实验开辟了新的可能性，其中调制电位远小于弹性平均自由程。本研究的目的是对电子系统进行基础研究，并开发新的跨学科技术，用于使用聚合物控制电子性能。传统的光刻目前限于十分之一微米尺度的结构，而自组装聚合物具有5-50纳米尺度的间距。二嵌段共聚物已被这些研究人员用作光刻掩模，在3英寸晶片上以数万亿结构的密度图案化半导体和金属。将对诱导的周期结构进行研究，以监测它们对金属、半导体和超导体的电子性质的影响。这些研究可能产生的设备包括量子点激光器和超密度存储器。预计电子可以调整到周期性结构的一些方式将在有机导体中的分子水平上看到，其中电子形成电荷密度波，并且在微米水平上，磁通量锁定在超导网格上的特定图案中。***

9976576ChaikinThis project uses a combination of magnetic fields, low temperatures, unusual materials, and novel lithographies to test some of the basic ideas of condensed matter physics. The Bechgaard salts (TMTSF)2 X (X=PF6, ClO4, etc.) are highly anisotropic electronic conductors, which exhibit many of the most interesting ground states in nature: metallic, superconducting, spin density wave, and quantum Hall effect. In addition, they show unique properties in a magnetic field where the magnetic length competes with the Fermi wave-vector to produce a cascade of phase transitions. These commensurability effects are also present in flux quantization experiments that are performed on patterned superconducting networks on a micron length scale, comparable to the coherence length. Similar coherent interference effects may occur in semiconductors and metals when patterned on the nanometer length scale. Our fabrication of patterns on this length scale, using diblock copolymers as lithographic masks opens up new possibilities for device experiments where the modulation potential is much smaller than the elastic mean free path.%%%The aim of this research is to make fundamental studies of electronic systems and the development of new cross-disciplinary techniques for using polymers to control electronic properties. Conventional lithography is presently limited to structures on the scale of tenths of microns whereas self-assembled polymers have spacings on a 5-50 nanometer scale. Diblock copolymers have been used by these researchers as lithographic masks to pattern semiconductors and metals at a density of trillions of structures on a 3-inch wafer. Studies will be made on the induced periodic structure to monitor their effect on the electronic properties of metals, semiconductors, and superconductors. Devices that may result from such studies include quantum dot lasers and ultra-dense memories. It is anticipated that some of the ways that electrons can adjust to periodic structures will be seen on the molecular level in the organic conductors where electrons form a charge density wave, and at the micron level where the magnetic flux locks into particular patterns on a superconducting grid. ***