Exotic Electronic Quantum Matter: Multipolar Order, Bogoliubov Fermi Surfaces, and Flat Bands
Abstract
The overarching theme of this proposal is the exploration of exotic electronic quantum states that go beyond widely studied paradigms. Two popular frameworks to realize and elucidate unusual electronic quantum matter are magnetic quantum criticality, which often emerges in d-electron and f-electron systems where the Coulomb repulsion is strong, and topological superconductivity induced by proximity effect in semiconductor-superconductor heterostructures. This project proposes three novel and promising directions that extend these ideas – quantum criticality and topological superconductivity – to little explored territories. One of the key ingredients underlying these research directions are systems with significant spin orbit coupling and in which the electrons have not only spin, but also other internal degrees of freedom, such as orbital, band, or valley. Two classes of exotic states enabled by these internal degrees of freedom will be thoroughly investigated. The first are states in which charge/magnetic higher-order multipolar electronic moments order spontaneously, opening the possibility of new types of quantum critical behaviors. The second consists of states in which the electrons form pairs with non-trivial structure in the internal space, resulting in a unique bulk superconducting state with topologically protected Fermi surfaces. Besides these two types of states, the project will also explore flat-band systems as a viable framework to realize exotic quantum states even when the Coulomb repulsion has a small magnitude. The key insight is the focus on a relatively unexplored set of interacting flat-band systems: Penrose quasicrystals. Their structure of zero-energy states offers unique advantages over other flat-band setups, which will enable the PI to address the important question of how the nature of the flat bands affects the instabilities caused by electronic interactions. These three inter-related thrusts will be explored by a combination of state-of-the art analytical, phenomenological, and numerical simulation methods, as well as collaborations with experimental groups.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 21, 2022
- Source ID
- FA95502110423XX0
Entities
People
- Rafael M Fernandes
Organizations
- Air Force Office of Scientific Research
- Regents of the University of Minnesota
- United States Air Force