Logarithmic negativity of the 1D antiferromagnetic spin-1 Heisenberg model with single-ion anisotropy

Abstract

We study the 1D antiferromagnetic spin-1 Heisenberg XXX model with external magnetic field B and single-ion anisotropy D on finite chains. We determine the nearest and non-nearest neighbor logarithmic entanglement LN. Our main result is the disappearance of LN both for nearest and non-nearest neighbor (next-nearest and next-next-nearest) sites at zero temperature and for low temperature states. Such disappearance occurs at a critical value of B and D. The resulting phase diagram for the behaviour of LN is discussed in the B - D plane, including a separating line - ending in a triple point - where the energy density is independent on the size. Finally, results for LN at finite temperature as a function of B and D are presented and commented.