Spin nematics and magnetization plateau transition in anisotropic Kagome magnets

We study S=1 kagome antiferromagnets with isotropic Heisenberg exchange $J$ and strong easy axis single-ion anisotropy $D$. For $D\gg J$, the low-energy physics can be described by an effective $S=1\mathrm{/}2$ $XXZ$ model with antiferromagnetic $J_z\sim J$ and ferromagnetic $J_{\perp }\sim J^2\mathrm{/}D$. Exploiting this connection, we argue that non-trivial ordering into a “spin-nematic” occurs whenever $D$ dominates over $J$, and discuss its experimental signatures. We also study a magnetic field induced transition to a magnetization plateau state at magnetization 1/3 which breaks lattice translation symmetry due to ordering of the $S^z$ and occupies a lobe in the $B\mathrm{/}{J}_z$-$J_z\mathrm{/}{J}_{\perp }$ phase diagram.