Ordering to two dimensional strained films

Oakland University, Rochester MI

Investigators

Abstract

NONTECHNICAL SUMMARY This award supports theoretical research and education devoted to the study of ultra-thin coatings or films on metallic surfaces with emphasis on novel materials with a particular honeycomb crystalline symmetry. Examples include graphene and hexagonal boron nitride. These films have been shown to possess unusual electronic and mechanical properties that many researchers are working toward exploiting for technological applications. The award addresses the development of new theoretical methods for predicting the growth and properties of such films under different experimental conditions. This award supports training graduate students in sophisticated mathematical and computational techniques and the PI's broader educational activities through summer schools, tutorials, and workshops. This project involves international collaborations with researchers in Europe, South America, and Africa. TECHNICAL SUMMARY This award supports theoretical research and education in materials physics with specific applications to the growth of two-dimensional or quasi two-dimensional films on metallic substrates. The coupling between the film and substrate gives rise to strain induced patterning and interesting commensurate/incommensurate phase transitions. Modeling such systems is complicated by the many possible length scales involved as the size of the patterns is inversely proportional to the film/substrate misfit strain in the weak adhesion limit and can diverge near the commensurate/incommensurate transition. To overcome this difficultly the PI plans to develop a model based on the phase field crystal model that can be used to study micron sized systems and incorporates atomistic details of the film/substrate interaction, elasticity and dislocations. The PI will examine the ordering of honeycomb monolayers on triangular and honeycomb substrates. The results of this work will be applicable to materials systems such as graphene, hexagonal boron nitride and molybdenum disulphide. The goal of this research is to predict the nature of the patterns that form as a function of misfit strain, adhesion strength and external conditions such as temperature. This award supports training graduate students in sophisticated mathematical and computational techniques and the PI's broader educational activities through summer schools, tutorials, and workshops. This project involves international collaborations with researchers in Europe, South America, and Africa.