The structure phase transition in atom-wide Co wires on a vicinal Cu{111} surface

• Co wire on a vicinal Cu(111) have two ferromagnetic states.
• In the first state the Co wire consists of dimers, while in the second state the distance between atoms in Co wire is equal.
• Dimerized structural phase of Co wire is a low-temperature phenomenon, occurring only below a critical temperature.
• The phase transition temperature depends drastically on the length of the wire and the tip bias.

The ab initio calculations are performed to study the structure of atom-wide Co wire on a vicinal Cu{111} surface. We have found two ferromagnetic states of Co wires. In the first state the Co wire consists of dimers, while in the second state the distance between atoms in Co wire is equal. Using Monte Carlo simulations we demonstrated the structure phase transition in a Co wire. Moreover, the phase transition temperature was determined and the size-effect was studied.