NSF Award
2436557
Non-technical Description<br/><br/>This research addresses the properties of a new class of ultra-thin quasi-two-dimensional semiconductors with intrinsic magnetic properties. The exotic properties of this new class of semiconductors make them particularly interesting for fundamental science research and practical applications. The investigators will explore the electronic, magnetic, and thermal properties of these unique materials with thicknesses of a few-atomic layers only. The PIs will also investigate the potential of these materials for use in devices with novel functionality that operate at high speed with low-energy dissipation. This research aligns with the Nation’s need for the development and research of novel semiconductor materials and devices under the recent CHIPS and Science Act. The interdisciplinary nature of the project will facilitate the involvement of students in the proposed research and contribute to undergraduate and graduate STEM education. The project team has developed a detailed Broadening Participation Plan that will impact the K-12, undergraduate, and graduate education of minorities underrepresented in STEM fields.<br/><br/>Technical Description<br/><br/>Transition-metal phospho-trichalcogenides span a wide variety of compounds with different electronic, magnetic, and phonon properties. These materials are one of a few van der Waals layered structures which can have intrinsic antiferromagnetism, even at mono-layer thickness. The band gap of these materials varies from ~1.3 eV to ~3.5 eV based on the type of its transition- metal element. Theory suggests that the application of gate bias and strain can induce phase transitions in these materials, changing their properties. While electrical insulators and conductors with AFM spin order have been studied extensively, little is known experimentally about antiferromagnetic layered semiconductors. This project aims to investigate the electron, phonon, and magnon properties of these unique materials at single- and few-layer structures, and to assess the possibilities of controlling their properties for enabling novel device functionalities. To achieve these goals, various types of these compounds will be synthesized and characterized using cryogenic micro – Brillouin – Raman spectroscopy, and electrical and thermal transport measurements. The results of this interdisciplinary research will add to the core knowledge in several areas of material science and electrical engineering, thereby delivering a transformative impact for applications of antiferromagnetic layered semiconductors. The intellectual merit of this project include knowledge of phonon and magnon band structures, and their modification with the thickness, strain, and electric bias; experimental data for controlling the Néel temperature in two- dimensional antiferromagnetic semiconductor films; mechanisms and methods for tuning the phase transitions in AFM semiconductors under the action of gate and strain; innovative approaches for enabling novel device functionalities via control of the electron, phonon, and magnon states in two-dimensional antiferromagnetic semiconductors.<br/><br/>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.
