Exploring Study of Novel Properties in Artificially Stacked Materials Grown by van der Waals Epitaxy

该项目已经完成，以创造由高度不均匀的层组成的新的人工堆叠材料，并探索它们所表现出的新特性。通过推广我们发展的范德华外延的思想，我们成功地生长了各种异质结构。悬挂键终止的概念使得在普通的三维材料如GaAs和Si上生长许多分层材料成为可能。我们还成功地制备了富勒烯和多种有机分子材料的良好外延膜。利用静电相互作用实现晶格不匹配的碱金属卤化物或极性有机材料在碱金属卤化物上的异质外延，也增加了异质外延材料的可能组合。发现和研究的新特性包括STM图像中的Moiree类型调制，超薄膜中的多型和电荷密度态的形成，通过堆积来控制酞菁薄膜的光学性质，以及碱卤化物超薄外延薄膜中表面极化子色散的异常。采用蒙特卡罗研究、能带计算、量子蒙特卡罗计算等分析方法，对人工堆积结构中的晶体生长、晶体结构、电子性质、超导介电性质等进行了理论研究。在一类由载流子带和绝缘带相互作用组成的排斥相互作用的电子系统中，已经证明了由于非延迟吸引而产生的超导电性。

This project has been fulfillled to create new artificially stacked materials made of highly heterogeneous layrs and to explore novel properties they show. By extending the idea of van der Waals epitaxy developed by us we have succeeded to grow various kinds of heterostructures. The concept of dangling bond termination has made it possible to grow many layred materials on such ordinary three-dimensional materials as GaAs and Si. Good epitaxial films of fullerene and many organic molecular meterials have also been fabricated successfully. Success in heteroepitaxy between lattice-mismatched alkali halides or polar organic materials on alkali halide by using electrostatic interaction has also increased the possible combination of materials in heteroepitaxy. New properties found and investigated in the present project include moiree-type modulation in STM image, polytype and charge density state formations in ultrathin films, control of optical properties of phthalocyanien films by stacking and anomaly in surface polariton dispersion in ultrathin epitaxial films of alkali halides. Crystal growth, crystal structure, electronic properties, superconductivity dielectric properties in the artificially stacked structures have been investigated theoretically by means of Monte Carlo study, Band, calculation, Quantum Monte Carlo study of analytical method. The occurrence of superconductivity due to nonretarded attraction has been demonstrated in a class of repulsively interacting electron systems that consist of a carrier band interacting with an insulting band.