Co adatoms on the Cu(111) surface are known to exhibit strong ferromagnetic character of the exchange interaction, if coupled directly, and explicit antiferromagnetic one, if separated by two Cu atoms [1]. Our calculations, carried out in terms of Heisenberg model, re-vealed a possibility to design an elementary transmitting unit by adjusting geometry of the system. The transmittance of the unit was found stable up to ≈100 Å (100 bonds of FM chain) in small magnetic fields (~1 meV) at room temperature
