Dynamics and Quantum Phase Transitions of Chiral Fermi Liquids

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NONTECHNICAL SUMMARYThis award supports theoretical research and education that focuses on understanding and describing the correlated motion of electrons in materials as they interact with each other and the underlying atomic nuclei arranged on a crystalline lattice. A key ingredient is the electron spin. Quantum mechanically, the electron behaves like a very tiny top, and because of its charge like a tiny magnet as well. As the electron moves through the crystalline lattice, the electric field of the nuclei looks like a magnetic field which interacts with the magnetic character of the electron and so, the direction of its spin. In this research project, the PI will develop a theoretical description of electrons that interact strongly with each other and with the periodic lattice of nuclei through its spin in natural and artificially constructed crystalline materials. The PI will investigate a phenomenon which results from the interplay between the electrons interacting with the lattice and electrons interacting with each other; this leads to a new type of spin wave which might be used to carry data in computing devices. These spin waves can provide transfer of spin information over macroscopic distances with virtually no loss of energy, and allow for the implementation of new computing concepts. In connection with the research, the PI will develop a new mini-course on subjects relevant to this award for a multi-faculty course "Advanced Topics in Condensed Matter Physics" and organize an international workshop on quantum phase transitions. The significance of the research results will be communicated to a broader audience through the Funsize Physics website and public lectures.TECHNICAL SUMMARYThis award supports theoretical research and education to develop and pursue the consequences of a consistent theory of materials systems with strong correlations among electrons and among spin and orbital degrees of freedom, a chiral Fermi liquid theory. The PI will explore predictions of this theory with consequences accessible to experiment. The research involves the identification and investigation of possible new phases of electronic matter in materials with strong spin-orbit-coupling and analyses of various experimental fingerprints of the interplay between spin-orbit coupling and electron-electron interaction. The main thrusts of the project include developing: i) a theory of electron-and electron-dipole spin resonance effects in a chiral Fermi liquid; ii) a many-body theory of Raman scattering from collective spin excitations in a chiral Fermi liquid; iii) a theoretical analysis of recently observed chiral spin waves and chiral excitons at the surface of a three-dimensional topological insulator (bismuth selenide); iv) an analysis of possible nematic phases of a two-dimensional electron system with SOC; and v) an analysis of the competition among possible instabilities in the spin channel of a non-chiral Fermi liquid. In connection to the research, the PI will develop new mini-courses on subjects relevant to this award for a multi-faculty course "Advanced Topics in Condensed Matter Physics" and will organize an international workshop on quantum phase transitions. The significance of the research results will be communicated to a broader audience through the Funsize Physics website and public lectures.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.