  We study the capacity of antiferromagnetic lattices of varying geometries to
entangle two additional spin-1/2 probes. Analytical modeling of the Quantum
Monte Carlo data shows the appearance of a robust gap, allowing a description
of entanglement in terms of probe-only states, even in cases where the coupling
to the probes is larger than the gap of the spin lattice and cannot be treated
perturbatively. We find a considerable enhancement of the temperature at which
probe entanglement disappears as we vary the geometry of the bus and the
coupling to the probes. In particular, the square Heisenberg antiferromagnet
exhibits the best thermal robustness of all systems, whereas the three-leg
ladder chain shows the best performance in the natural quantum ground state.
