Spontaneous Formation of Exceptional Points at the Onset of Magnetism

Abstract

We reveal how symmetry protected nodal points in topological semimetals may be promoted to pairs of generically stable exceptional points (EPs) by symmetry-breaking fluctuations at the onset of long-range order. This novel route to non-Hermitian (NH) topology is exemplified by a magnetic NH Weyl phase spontaneously emerging at the surface of a strongly correlated three-dimensional topological insulator when entering the ferromagnetic regime from a high temperature paramagnetic phase. Here, electronic excitations with opposite spin acquire significantly different life-times, thus giving rise to an anti-Hermitian structure in spin that is incompatible with the chiral spin texture of the nodal surface states, and hence facilitates the spontaneous formation of EPs. We present numerical evidence of this phenomenon by solving a microscopic multi-band Hubbard model non-perturbatively in the framework of dynamical mean-field theory.

6 pages, 4 figures

References in corpus (17)

• Topological Insulators with Inversion Symmetry
• Continuous-time Monte Carlo methods for quantum impurity models
• The physics of exceptional points
• Strong electronic correlations from Hund's coupling
• Efficient Light Funneling based on the non-Hermitian Skin Effect
• Topological phases in the non-Hermitian Su-Schrieffer-Heeger model
• Topological Transition in a Non-Hermitian Quantum Walk
• Simplified topological invariants for interacting insulators
• Non-Hermitian Skin Effects in Hermitian Correlated/Disordered Systems: Boundary-Sensitive/Insensitive Quantities and Pseudo Quantum Number
• Topological antiferromagnetic phase in a correlated Bernevig-Hughes-Zhang model
• Classification of Exceptional Nodal Topologies Protected by $\mathcal{P}\mathcal{T}$ Symmetry
• R-DMFT study of a non-Hermitian skin effect for correlated systems: analysis based on a pseudo-spectrum
• Fourth-Order Exceptional Points in Correlated Quantum Many-Body Systems
• Exceptional points in the one-dimensional Hubbard model
• Realistic theory of electronic correlations in nanoscopic systems
• Surface exceptional points in a topological Kondo insulator
• Local vs non-local correlation effects in interacting quantum spin Hall insulators

Cited by in corpus (4)

• Universality in driven open quantum matter
• Protection of Correlation-Induced Phase Instabilities by Exceptional Susceptibilities
• Laser induced $\mathcal{P}\mathcal{T}$-symmetry breaking in the fluctuations of electronic fluids
• Exact solutions for topological surface states of three-dimensional lattice models