Kavli Affiliate: Leon Balents
| First 5 Authors: Chuang Chen, Chuang Chen, , ,
| Summary:
We design a lattice model of non-compact U(1) gauge field coupled to fermions
with a flavor chemical potential and solve it with large-scale determinant
quantum Monte Carlo simulations. For zero flavor chemical potential, the model
realizes three-dimensional quantum electrodynamics (QED$_3$) which has been
argued to describe the ground state and low-energy excitations of the Dirac
spin liquid phase of quantum antiferromagnets. At finite flavor chemical
potential, corresponding to a Zeeman field perturbing the Dirac spin liquid, we
find a ”chiral flux” phase which is characterized by the generation of a
finite mean emergent gauge flux and, accordingly, the formation of relativistic
Landau levels for the Dirac fermions. In this state, the U(1)$_m$ magnetic
symmetry is spontaneously broken, leading to a gapless free photon mode which,
due to spin-flux-attachment, is observable in the longitudinal spin structure
factor. We numerically compute longitudinal and transverse spin structure
factors which match our continuum and lattice mean-field theory predictions.
Further, sufficiently strong fluctuations of the emergent gauge field give rise
to an antiferromagnetically ordered state with gapped Dirac fermions coexisting
with a deconfined gauge field. We also find an interesting intermediate phase
where the chiral flux phase and the antiferromagnetic phase coexist. We argue
that our results pave the way to testable predictions for magnetized Dirac spin
liquids in frustrated quantum antiferromagnets.
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