Effect of a Dipole–Dipole Interaction on the Time of Magnetization Reversal of Finite-Length Atomic Chains

The magnetization reversal of atomic chains on metal surfaces has been theoretically studied using the analytical method developed earlier and the geodesic nudged elastic band method. The atomic chains can be divided into the following three types: chains with a small, intermediate, and large domain wall width. A dipole–dipole interaction is shown to cause an increase in the average spontaneous magnetization reversal time of FM|| and AFM⊥ chains and a decrease in the magnetization reversal time of FM⊥ and AFM|| chains. For FM⊥ and AFM⊥ chains with a medium-width domain wall, taking into account a dipole–dipole interaction leads to the appearance of an energy barrier between two states of a domain wall differing in the direction of rotation of magnetic moments. The magnetization reversal of atomic chains from the third type can occur in the following two ways: all magnetic moments are reversed either simultaneously or one by one. The transition from one magnetization reversal mode to another occurs at a critical length N0. The effect of a dipole–dipole interaction is most significant when the chain length is close to N0. Numerical estimations have shown that taking into account a dipole–dipole interaction can change the magnetization reversal time of a chain by an order of magnitude in some cases.