The ultimate limit in miniaturization of nanomagnets was achieved in 2016: individual Ho atoms present remanence when deposited on an atomically thin layer of MgO coating a silver film was reported by scientists from EPFL and ETH, in Switzerland. Before that, the smallest nanomagnets reported, attending to the number of magnetic atoms, were double decker phthalocyanes molecules with only one rare-earth atom. Other systems presenting remanence are nanoengineered Fe chains, deposited on Cu 2 N/Cu(100) surfaces, showing either Neel or ferromagnetic ground states with in systems with as few as 5 Fe atoms with S=2. Canonical single-molecule magnets are the so-called Mn 12 and Fe 8 systems, with 12 and 8 transition metal atoms each and both with spin 10 (S = 10) ground states.