Imaging of Electronic Correlations and Symmetry Breaking Effects in Twisted Van der Waals Materials

California Institute Of Technology, Pasadena CA

Investigators

Abstract

Non Technical: This project aims to explore the electronic properties of engineered materials that are assembled one atomic layer at a time, starting from individual sheets of graphene and certain semiconductors, so-called transition metal dichalcogenides. For precise well-defined rotational misalignment angle between the layers, electrons in these materials strongly interact which leads to the emergence of correlated quantum electronic phases. The research team will image these emerging phases using scanning tunneling microscopy and spectroscopy techniques in various geometries. This approach will allow the team to gain insights into how the microscopic properties of correlated phases relate to their overall transport signatures. This information can be used to develop novel electronic quantum devices. The team will disseminate the project results through international conferences, journal articles, invited talks, publicly available blog posts, and educational videos targeting a broad audience. Besides the research component, this project aims to provide ample opportunities for integrating undergraduate education and increasing diversity through summer internships and programs for underrepresented minorities and outreach activities targeting high-school students and teachers from the Pasadena School District. Technical: The discovery of layered quasi-two-dimensional crystals enabled a new way of designing tunable electronic systems in which electron-electron interactions are controlled through the rotational alignment (twist) of the stacked layers. The focus of this project is to explore properties of emerging correlated quantum electronic phases, including superconductivity and orbital ferromagnetism, in twisted multi-layer graphene and transition metal dichalcogenides heterostructures. One of the main goals is to establish a basic understanding of underlying symmetries and symmetry breaking phenomena that occur in these emerging phases using scanning tunneling microscopy and spectroscopy and by studying heterostructures in gate-tunable multi-terminal geometries. This research project is accompanied by an extensive mentoring and outreach plan aimed to prepare graduate and undergraduate students for successful careers in science and industry and help educate the public about quantum science and nanotechnology. 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.