Topological Straintronic Devices

Indiana University, Bloomington IN

Investigators

Abstract

Nontechnical: Semiconductor technologies have fueled the explosive growth of information-age technologies over the last half century. Further advances, however, are becoming increasingly difficult as devices dimensions approach atomic scales. This challenge requires new approaches that harness quantum phenomena. Novel electronic devices that exploit quantum properties have the potential for better device reliability and lower power consumption. Quantum technologies bring their own challenges. In particular, environmental effects can corrupt quantum information and significant resources are required for error correction. Topological materials offer great potential to address this problem because of their unique properties. In particular, quantum states are topologically protected by symmetries and are less subject to corruption. In this project elastic strain rather than electric or magnetic fields will be used to control electronic states in devices. Logic gates and other electronic devices are expected to be more reliable and use less power than conventional devices based on complementary metal oxide semiconductors. Interactive and engaging educational outreach programs will be integrated with the research project. These include Science Blog writing and Materials and Device Exhibits. These outreach efforts will promote scientific literacy to the general public and improve science appreciation by local K-12 students. This in turn will attract such students to modern science and technology in the early stages of their education. Finally, the participation of underrepresented groups in scientific research will be enhanced. Technical: This collaborative research project concerns novel strain-electronic (or straintronic) nanowire devices built upon two classes of topological materials, topological crystalline insulators (TCIs) and Weyl semimetals (WSMs), which host massless Dirac fermions on their surfaces and Weyl fermions with definite chirality in their bulk, respectively. These extraordinary surface or bulk states are topologically protected by symmetries and are rather robust against impurities, defects and disorder. Electronic devices exploiting these quantum/topological states are likely to have significantly improved reliability and/or reduced power consumption relative to conventional semiconductor-based electronics. The overall objective of this project is to study and manipulate the exotic quantum properties of Dirac and Weyl fermions in topological devices utilizing controllable elastic strain towards low-power, highly reliable electronic applications. In contrast to previous studies of bulk crystals and thin films, the proposed research will focus on nanowire/nanoribbon-based devices that harbor exceptional features for straintronic studies and applications. The success of the project will be built on the two PIs' existing collaboration, extensive familiarity with topological materials, and complementary expertise on material synthesis, device fabrication, magneto-transport studies, and theoretical modeling of electronic systems. The combined theoretical and experimental studies of strain-driven topological phase transitions and associated quantum transport properties will offer new paradigms for fundamental, potentially exploitable physics in electronic systems. The proposed research is also anticipated to represent a key step in establishing a new research area, topological straintronics: the manipulation of topological quasi-particles with controllable elastic strain. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.