RII Track-4:NSF: Resistively-Detected Electron Spin Resonance in Multilayer Graphene

This Research Infrastructure Improvement Track-4 EPSCoR Research Fellows project will provide a fellowship to an Assistant Professor and training for a postdoctoral fellow at Brown University. Spin is an intrinsic property of electrons, which is key to understanding electronic properties of quantum materials at low temperatures. For instance, magnetism occurs when spins of many electrons align in a preferred direction, whereas the nature of superconductivity is crucially dependent on the spin configuration of the underlying electron pairs. In atomically thin materials consisting of two to three layers of carbon atoms, the reduced dimension enhances Coulomb correlation (describes the correlation between the spatial position of electrons due to their Coulomb repulsion), which further amplifies the role of electronic spin. This project aims to develop an experimental method to directly probe the configuration of electron spins in these 2D materials. The proposed effort takes advantage of the state-of-the-art user facility at the National High Magnetic Field Lab. By exposing students and researchers to cutting-edge research in the national lab, the research and outreach program inspires and educates future scientists and engineers to take on leadership roles and pioneer innovations in the field of quantum science and quantum material research. The research project also aims to establish a user program located in Rhode Island, which promises to have wide wide-ranging impact on training Rhode Island’s quantum-deficient workforce by providing research and intern positions for different levels of students. The low-temperature phase diagram of strongly correlated 2D materials hosts many exotic quantum phases, such as superconductivity and ferromagnetism. To understand the microscopic origin underlying these emergent phenomena, it is key to first identify the exact configuration of electronic spin. However, the lack of viable experimental methods presents a hurdle to uncovering the order in the spin degrees of freedom, which gives rise to one of the main challenges for research efforts aiming to better understand the nature of electronic states in 2D materials such as multilayer graphene. In this proposal, the PI puts forth a new paradigm of experimental methods that are capable of directly probing the nature of electronic spin, which utilizes resistively detected electron spin resonance measurement. Moreover, The PI will investigate the Coulomb-driven process of spontaneous rotational symmetry breaking. Recent experimental progress demonstrated that spontaneous rotational symmetry breaking can be characterized based on angle-resolved nonreciprocal transport measurement. Building on these developments, the proposed research project will investigate the electronic spin configuration in multilayer graphene, such as Bernal stacked bilayer graphene and magic-angle twisted trilayer graphene, along with its connection to the process of spontaneous rotational symmetry breaking. Results from this project will have a far-reaching impact by providing new insights into the nature of electronic orders stabilized by the interplay between strong correlation and nontrivial topology. The proposed project will utilize the state-of-the-art user facility at the National High Magnetic Field Lab (NHMFL), where capable staff scientists provide strong technical support. 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.