The goal of this proposal is to gain a fundamental understanding of the properties of chiral charge density wave systems and create new electronic devices exploiting unique advantages of the chiral state of the collective charge system. Understanding the nature of chiral charge density wave and learning how to manipulate chiral charge domains will be transformative to the condensed matter physics and it will open the doors to devices based on collective electron excitations. The main advantage of using collective charge systems for electronics is lower power dissipation at high device densities. The fundamental studies will involve both macroscopic and atomic scale investigations of the chiral charge density wave states in carefully engineered two-dimensional materials. The program will provide students and young researchers with necessary tools to carry out modern fundamental research in the fields of materials science, condensed matter physics and electronic device engineering. Since the designed research activities are highly interdisciplinary, the students will be stimulated to take classes across disciplines, such as nanoscience, electron and scanning probe microscopy and nanofabrication. The plan is to broaden participation and appreciation of students through (a) incorporating elements of the research in existing nanoscience, nano-electronics and solid-state physics courses at both the undergraduate and graduate level; (b) train students to use state of the art fabrication and characterization tools and (c) expose the students to research enterprise and collaborative research across different organizations. This work should lead to training a PhD student and several undergraduate students. Outreach to local area high schools through senior thesis work experience and science research clubs as well as College's open houses are part of the overreaching strategy to prepare high school students to pursue science and engineering degrees.
Chirality breaks down the spatial inversion symmetry and results in unexpected new electronic properties, in particular in systems with reduced dimensionality. In many cases the electronic chirality is facilitated by the specific structure of the system in which it emerges, either on atomic scale or on mesoscopic scale. Recently, it was discovered that one of the well-studied macroscopically correlated electronic state, the charge density wave, also exhibits chiral properties. This proposal explores the opportunity to use the nanometer-size domains of opposite chirality that are separated with domain walls as basic elements for memory and logic units. The goal of the research is to gain a fundamental understanding of the nature of the coupling of the chiral charge density waves with external perturbations, such as light, quasi static electric and magnetic fields with the aim of actively controlling and measuring the chiral state of individual charge density wave domains. Successful manipulation and read-out of the chiral state of individual several nanometer-size domains would enable utilization of the chiral charge systems in information storage and processing. To achieve this goal the investigators will synthesize single crystals of chiral charge density wave materials, conduct local scanning probe characterization as well as bulk characterization on both single crystal and exfoliated few layer crystals of dichalcogenides. Scanning tunneling microscopy on few-layer single crystals as well as coupling the light to the scanning tunneling microscopy junction will play important role in identifying practical regimes for chiral domain manipulation. The use of collective chiral states in electronic devices could dramatically extend the current down-scaling limit of complementary metal-oxide semiconductors that is set by the level of power dissipation in incoherent electron based devices. The fundamental studies will involve both macroscopic and atomic scale investigations of the chiral charge density wave states in carefully engineered two-dimensional materials, thus clearly exposing the complex mesoscopic physics that couples excitonic and charge density wave correlations
