Non-Technical: The last decade has seen tremendous advances in the realization of new materials classes with unique properties such as topological insulators and phase change materials. This proposal seeks to harness the properties of these new materials classes to build a new generation of strain-based devices. Strain control of devices is at the beginning stages with many theoretical predictions and little experimental work. Moreover, much of the predictions of strain induced phase transitions are yet to be tested. Our success in creating strain and gated devices will allow us to tune bulk band structure and transport properties into metallic and insulating regimes thereby creating the basis for future straintronic devices. The conditions under which we are able to realize reversible phase transitions from insulating to metallic in topological materials will provide important information for the theoretical understanding of these systems. Realizing, characterizing, and measuring strain tunable systems will allow us to understand and explore strain dependent materials properties for applications such as optical and electrical storage devices, solid-state displays, photonic memories, plasmonic-based circuits, optical modulators, and computing. Undergraduates, graduate students and post-docs involved in this project will be trained on materials and instruments at the forefront of today's research. The success of the project will enhance research experience for women in physics. Many of the undergraduates, graduate students and post-docs working in the PIs' labs are from under represented groups. The PI's integrated outreach and education activities will expose talented high school students to cutting edge research.
The unique properties of topological insulators, topological crystalline insulators, and transition metal dichalcogenides, as well as their potential tunability by strain and doping make them very attractive for future applications. Our ability to harness the extraordinary properties of this new generation of materials however depends heavily on our ability to manipulate their electronic properties. While a whole host of potential devices have been proposed, very few have been realized so far. This collaborative research project describes the PIs plans to investigate different avenues to use strain to control Dirac surfaces states and phase change materials. To achieve this, the PIs will combine their considerable expertise in these materials classes with advanced measurement techniques. The success of the project hinges on a tight feedback loop between molecular beam epitaxy thin film growth, characterization using low temperature scanning tunneling microscopy, and spin and charge transport measurements. Thin films of 3D topological insulators, topological crystalline insulators and phase change materials will be grown characterized with a range of probes including scanning tunneling microscopy, X-ray scattering and atomic force microscopy. Strain devices for transport measurements will be made using both thin films as well as exfoliated flakes. The goal is to create materials with specific properties tailored for device applications through reduced dimensionality and strain.
