  The controlled switching between two quasi-stable Neel states in adsorbed
anti-ferromagnetic Fe chains has recently been achieved by Loth et al [Science
335, 196 (2012)]. In order to rationalize their data, we evaluate the rate of
tunneling electron-induced switching between the N\'eel states. Good agreement
is found with the experiment permitting us to identify three switching
mechanisms: (i) low-bias direct electron-induced transitions, (ii)
intermediate-bias switching via spin-wave-like excitation, and (iii) high-bias
transitions mediated by domain wall formation. Spin correlations in the
anti-ferromagnetic chains are the switching driving force leading to a marked
chain-size dependence.
