Ground state entanglement entropy in a coupled spin-1/2 dimer with Dzyaloshinsky-Moriya interaction

We study the ground state entanglement entropy in a spin-1/2 dimer with Dzyaloshinsky-Moriya (DM) and Heisenberg interactions in a Zeeman field. For a fixed magnitude of the DM vector, the ground state entanglement entropy increases from the ferromagnetic to the anti-ferromagnetic limits of the Heisenberg interaction. In the case of anti-ferromagnetic interactions with strong Zeeman splitting there exists a non-zero value of the DM magnitude that minimizes ground state entanglement.