Condensed Matter Theory Seminar - LSU Authors: J. A. Sauls
Where: Department of Physics & Astronomy, Louisiana State University, Baton Rouge, LA
March 26, 2024

Abstract: Broken symmetries and emergent topology in condensed matter systems have implications for the spectrum of Fermionic excitations confined on surfaces or topological defects. The Fermionic spectrum of confined (quasi-2D) ³He-A consists of branches of massless chiral Fermions confined on a boundary. The negative energy states determine the ground-state edge current and angular momentum, L_z = (N/2) ħ, for a macroscopic system of N/2 Fermion paires. I discuss the effects of wave function overlap, and hybridization between edge states confined near opposing surfaces. Under sufficiently strong confinement, a chiral superfluid/superconductor undergoes a sequence of phase transitions, including a pair density wave (PDW) phase that spontaneously breaks translational symmetry. The PDW phase that forms is a periodic array of chiral domains with alternating chirality, separated by domain walls that form a soliton lattice. The PDW phase is driven by the competition between the edge states and a new branch of chiral fermions bound to the domain walls.

This research was supported by NSF Grant: DMR-1508730

1. Hao Wu and J. A. Sauls,  Weyl Fermions, Confinement & Edge State Hybridization in Chiral Superfluid ³He-A J.Phys. Cond. Matt. (IOP), 35, 495402 (2023)

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