arXiv:1701.01465 · Physical review. B./Physical review. B
Phase diagram of weakly coupled Heisenberg spin chains subject to a uniform Dzyaloshinskii-Moriya interaction
Wen Jin, Oleg A. Starykh
Abstract
Motivated by recent experiments on spin chain materials ${\mathrm{K}}_{2}{\mathrm{CuSO}}_{4}{\mathrm{Cl}}_{2}$ and ${\mathrm{K}}_{2}{\mathrm{CuSO}}_{4}{\mathrm{Br}}_{2}$, we theoretically investigate the problem of weakly coupled spin chains (chain exchange $J$, interchain ${J}^{\ensuremath{'}}$) subject to a staggered between chains, but uniform within a given chain, Dzyaloshinskii-Moriya (DM) interaction of magnitude $D$. In the experimentally relevant limit ${J}^{\ensuremath{'}}\ensuremath{\ll}D\ensuremath{\ll}J$ of the strong DM interaction the spins on the neighboring chains are forced to rotate in opposite directions, effectively resulting in a cancellation of the interchain interaction between components of spins in the plane normal to the vector $\mathbit{D}$. This has the effect of promoting a two-dimensional collinear spin density wave state, which preserves U(1) symmetry of rotations about the $\mathbit{D}$ axis. We also investigate response of this interesting system to an external magnetic field $\mathbit{h}$ and obtain the h-D phase diagrams for the two important configurations $\mathbit{h}\ensuremath{\parallel}\mathbit{D}$ and $\mathbit{h}\ensuremath{\perp}\mathbit{D}$.