ИСТИНА

In 1958 Dzyaloshinskii has suggested a new type of interaction between magnetic atoms in order to explain the weak ferromagnetism of antiferromagnetic crystals α-Fe2O3, MnCO3, and CoCO3 [1]. Latter Moriya has interpreted this interaction as an anisotropic superexchange interaction [2]. Now this interaction is called the Dzyaloshinskii-Moriya interaction (DMI). The interest to DMI has arisen after the observations of strong DMI in transition metal films [3]. DMI in layered structures can lead to formation of different magnetic structures like chiral domain walls, chiral bubbles and skyrmions. Strong DMI in atomic chains also can lead to some interesting phenomena. For example, biatomic Fe chains on the Ir(001)(5×1) surface have a DMI-induced noncollinear magnetic ground state [4]. Moreover, the DMI can significantly change the energies of excited states even if the ground state of an atomic chain is collinear. Using ab initio calculations the significant DMI in Co and Fe chains on Pt(664) surface has been predicted [5]. It has been shown that the infinitely long Co and Fe chains have the collinear ferromagnetic ground state, but DMI changes the energies of the excited states. The magnetic properties of the atomic chains can be satisfactorily described in the framework of some effective theory including the exchange interaction, the magnetic anisotropy energy (MAE), DMI, and the interaction with the external fields. The parameters of the effective theory have been taken from Ref. [5]. For the numerical calculations the geodesic nudged elastic band (GNEB) method [6] is employed. For analytical calculations we use the continuous XY-model. Energy barriers for magnetization reversal of the finite-size Co and Fe chains on Pt(664) surface are calculated with taking the Dzyaloshinskii-Moriya interaction into account. It has been found that the ground states of such atomic chains are noncollinear. The magnetization reversal of short atomic chains occurs without the formation of domain walls. At the same time, the magnetization reversal of longer atomic chains occurs via the formation of the clockwise domain wall (CDW) or the anticlockwise domain wall (ACDW). It is interesting that mechanisms of the magnetization reversal of the Co and Fe atomic chains are different. Knowing of the energy barriers allows to calculate the magnetization reversal times [7] both in zero and nonzero external magnetic fields. After that we calculate the magnetization curves and the coercivity of the finite-size Co and Fe chains. Here we focus on comparison of results for Co and Fe atomic chains. The research is carried out using the equipment of the shared research facilities of HPC computing resources at Lomonosov Moscow State University [8]. The investigation is supported by the Russian Science Foundation (Project No. 21-72-20034).