New quantum states in perfectly stoichiometric high-quality single crystals obtained by solid-state electro-transport

提纯和改善材料结晶质量的新方法一再导致科学知识和技术的进步。例子包括(I)汉弗莱·戴维爵士(1807)通过电解分离金属元素，这是制造现代高温合金的重要一步；(Ii)简·Czochralski(1909)的晶体生长方法，现在用于为每年3000亿美元的硅半导体行业生产纯单晶，和(Iii)William G Pfan(1951)的区域精炼的发展，使高纯度的Ge和GaAs变得可用，导致了新的现象的发现，如在非常高质量的GaAs中发现的分数量子霍尔态。凝聚态物理学界广泛接受，存在比目前已知的更多的电子物质的自组织状态。这种物质状态的发现将可与前几个世纪铁磁性、传统超导或量子霍尔态的发现相媲美。人们普遍认为，人们应该在材料的低温下寻找这样的状态，直到传统的电子态变得不稳定，特别是接近零温度连续相变。困难在于，与铁磁性和常规超导不同，要形成新的状态，宿主材料必须非常纯净，没有结构缺陷。对于非常规形式的超导，所需的完美程度的基准得到了很好的量化。然而，由于与整化学计量比的微小偏差导致的缺陷冻结，大多数材料不能以所需的完美程度结晶(即使在延长时间后也是如此)。这项拟议的研究将开发一种设备，将材料的组成调整到理想的整数值，实现纯度和结晶质量的飞跃。随后，我们将研究低温下新电子态的形成。虽然新态的形成在一般的理论基础上是可以预见的，但这些态的性质和电子结构是未知的。空间不均匀或振荡的电子结构是很强的理论可能性。实验中发现的状态可能会证实这样的预测，或者可能会像100多年前超导电性被发现时一样出人意料。成分调整将产生质量更好的晶体，也将使我们能够通过测量只有在极高质量的晶体中才能检测到的量子振荡，来推进对金属中非常规超导和电荷密度波的理解。

New methods for purifying and improving the crystalline quality of materials have repeatedly led to advances in scientific knowledge and technology. Examples include (i) Sir Humphry Davy's (1807) separation of metallic elements by electrolysis, a significant step towards making modern super-alloys, (ii) Jan Czochralski's (1909) method for crystal growth now used to produce pure single-crystals for the $300bn/year silicon semiconductor industry, and (iii) William G Pfann's (1951) development of zone-refining making available high purity Ge and GaAs leading to the discovery of new phenomena such as fractional quantum Hall states found in very high quality GaAs.It is widely accepted in the condensed matter physics community that many more self-organized states of electronic-matter exist than are presently known. The discovery of such states of matter would be comparable to the discovery of ferromagnetism, conventional superconductivity or quantum Hall states in preceding centuries. There is a widespread consensus that one should look for such states at low temperatures in materials driven to the point where conventional electronic states become unstable, specifically close to zero-temperature continuous phase transitions. The difficulty is that for the new states to form, unlike for ferromagnetism and conventional superconductivity, the host materials have to be extremely pure and free of structural defects. The benchmark for the level of perfection required is well quantified for non-conventional forms of superconductivity. Most materials, however, do not crystallize with the required perfection (even after annealing for extended times), owing to the freezing-in of defects resulting from small deviations from integer stoichiometry. The proposed research will develop apparatus to tune the composition of materials to ideal integer values, achieving a leap forward in purity and crystalline quality. Subsequently, the formation of new electronic states at low temperatures will be investigated. Although the formation of new states is anticipated on general theoretical grounds, the nature and electronic structure of these states is unknown. Spatially in-homogeneous or oscillating electronic structures are strong theoretical possibilities. The states found experimentally may confirm such predictions or might be as unexpected as superconductivity was when it was discovered just over 100 years ago. The better quality crystals that composition tuning will produce will also permit us to advance understanding of non-conventional superconductivity and charge density waves in metals by measuring quantum oscillations that are detectable only in crystals of extremely high quality.