Schwinger-boson approach to the kagome antiferromagnet with Dzyaloshinskii-Moriya interactions: Phase diagram and dynamical structure factors

We have obtained the zero-temperature phase diagram of the kagome antiferromagnet with Dzyaloshinskii-Moriya interactions in Schwinger-boson mean-field theory. We find quantum phase transitions (first or second order) between different topological spin-liquid and Neel-ordered phases (either the root 3 x root 3 state or the so-called Q = 0 state). In the regime of small Schwinger-boson density, the results bear some resemblances with exact diagonalization results and we briefly discuss some issues of the mean-field treatment. We calculate the equal-time structure factor(and its angular average to allow for a direct comparison with experiments on powder samples), which extends earlier work on the classical kagome to the quantum regime. We also discuss the dynamical structure factors of the topological spin-liquid and the Neel-ordered phases.