Spin-charge Separation in Nodal Antiferromagnetic Insulator

TL;DR

This paper investigates spin-charge separation in a nodal antiferromagnetic insulator using 2D Hubbard models, revealing novel phenomena like fermionic and bosonic solitons with induced quantum numbers, suggesting universality across systems.

Contribution

It demonstrates spin-charge separation phenomena in 2D AF insulators with Dirac fermions, introducing novel soliton behaviors and induced quantum numbers.

Findings

Half skyrmions become fermionic particles due to induced spin moments.

Adding electrons or holes transforms solitons into bosonic particles.

Induced quantum numbers on solitons may be universal in spin-charge separation.

Abstract

In this paper, by using two dimensional (2D) Hubbard models with pi-flux phase and that on a hexagonal lattice as examples, we explore spin-charge-separated solitons in nodal antiferromagnetic (AF) insulator - an AF order with massive Dirac fermionic excitations (see detail in the paper). We calculate fermion zero modes and induced quantum numbers on solitons (half skyrmions) in the continuum limit, which are similar to that in the quasi one-dimensional conductor polyacetylene (CH)x and that in topological band insulator. In particular, we find some novel phenomena : thanks to an induced staggered spin moment, a mobile half skyrmion becomes a fermionic particle; when a hole or an electron is added, the half skyrmion turns into a bosonic particle with charge degree of freedom only. Our results imply that nontrivial induced quantum number on solitons may be a universal feature of spin-charge separation in different systems.