Experimental Studies of Organic Crystals, Metals and Superconductors

9976576 chaikin这个项目结合了磁场、低温、不寻常的材料和新的光刻技术来测试凝聚态物理的一些基本思想。贝加德盐（TMTSF） 2x （X=PF6， ClO4等）是高度各向异性的电子导体，在自然界中表现出许多最有趣的基态：金属态、超导态、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，其中磁长与费米波矢量竞争，产生级联相变。这些可通约性效应也存在于通量量子化实验中，这些实验是在微米长度尺度上的图案超导网络上进行的，与相干长度相当。类似的相干干涉效应可能发生在半导体和金属当图案在纳米长度尺度。我们使用双嵌段共聚物作为光刻掩模，在这种长度尺度上制造图案，为调制电位远小于弹性平均自由程的器件实验开辟了新的可能性。这项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，利用聚合物来控制电子性能。传统的光刻技术目前仅限于十分之一微米的结构，而自组装聚合物的间距在5-50纳米尺度上。这些研究人员将双嵌段共聚物用作光刻掩模，在3英寸晶圆上以数万亿个结构的密度对半导体和金属进行图案化。将研究诱导周期结构，以监测其对金属、半导体和超导体电子特性的影响。这些研究可能产生的设备包括量子点激光器和超密存储器。可以预见的是，在有机导体的分子水平上，电子可以形成电荷密度波，在微米水平上，磁通量锁定在超导网格上的特定模式，电子可以调整到周期性结构的一些方式将被看到。＊＊＊

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. ***