Gauge flux generations of weakly magnetized Dirac spin liquid in a kagom\'{e} lattice

Abstract

Inspired by the recent progress on the Dirac spin liquid and the kagom\'{e} lattice antiferromagnets, we revisit the U(1) Dirac spin liquid on the kagom\'{e} lattice and consider the response of this quantum state to the weak magnetic field by examining the matter-gauge coupling. Even though the system is in the strong Mott insulating regime, the Zeeman coupling could induce the internal U(1) gauge flux with the assistance of the Dzyaloshinskii-Moriya interaction. In addition to the perturbatively-induced non-uniform flux from the microscopic interactions, the system spontaneously generates the uniform U(1) gauge flux in a non-perturbative fashion to create the spinon Landau levels and thus gains the kinetic energy for the spinon matters. Renormalized mean-field theory is employed to validate these two flux generation mechanisms. The resulting state is argued to be an ordered antiferromagnet with the in-plane magnetic order, and the gapless Goldstone mode behaves like the gapless gauge boson and the spinons appear at higher energies. The dynamic properties of this antiferromagnet, and the implication for other matter-gauge-coupled systems are discussed.