CAREER: Electrical Control of Topological Phases in Layered Semimetals

University Of Arkansas, Fayetteville AR

Investigators

Abstract

This project is jointly funded by CMP Program and by the Established Program to Stimulate Competitive Research (EPSCoR). Non-technical abstract: The theory of topological phases and phase transitions, which is the seminal work of the 2016 Nobel Prize in Physics, establishes the foundation for a novel class of materials, referred as topological quantum materials. Electrons in these materials behaves like particles, thus enabling exploring high energy physics in tabletop experiments on solid state materials. These materials have been leading to deeper knowledge of important topics in physics, and display a kaleidoscope of novel electronic properties with great promise for technology applications, such as very high mobility or even dissipationless transport for energy-saving devices. The ability to manipulate these properties, particularly using electrical approaches to switch on and off, enhancing or suppression, is expected to enable a new generation of technology. This project aims to develop such ability to provide insights to implement those novel materials in technology applications. Integrated into the research activities is a broad scope of educational and outreach efforts to prepare a multi-talented and diverse quantum material workforce, including implementing a scalable approach to train an inclusive group of students of various levels, creating interdisciplinary courses to enhance material science education and prepare students for career paths, and partnering with a historically black college or university and a local underrepresented community to enhance research and education opportunities. Technical abstract: This project pursues the electrical control of topological electronic states by engineering lattice and time reversal symmetries in layered topological semimetals. Topological phase control is performed by electrostatic electron and hole doping and electrochemical intercalation in all-solid electrical double layer devices, which is based on the hypothesis that electron density acts as a tuning knob to modify these symmetries and drive topological phase transitions. This research aims to topological phase transitions between Dirac nodal-line semimetal, topological insulator, normal insulator, and Weyl semimetal phases. The obtained knowledge and developed techniques further enable the spatially selective control of topological phases to form lateral heterostructures, leading to a versatile platform to explore exciting quantum physics. Based on that, this project also targets to establish and demonstrate concrete strategies for realizing completely confined topological fermions and creating fundamentally new insights for novel confinement-induced phenomena in topological quantum materials. Finally, the education plan is closely integrated and leverages the research activities by training a diverse workforce with a broad mix of quantum-related skills, and in the long term, continue to benefit the condensed matter and materials science research. 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.