In this paper, we study the effect of a hole-shaped structural defect on the size and density, as well as the thermal stability of skyrmions and the skyrmion lattice in a magnetic monolayer with a triangular lattice and a planar Dzyaloshinskii−Moriya interaction, using the local relaxation method and Monte Carlo simulations. Achieving control over the skyrmion density opens possibilities for the design of functional skyrmion-based devices. It is shown that increasing the Dzyaloshinskii−Moriya parameter increases the skyrmion density, while the presence of an external magnetic field promotes the degeneracy of the mixed configuration of skyrmion-domains into the skyrmion lattice. We demonstrate that the presence of a hole-shaped defect does not affect the phase diagram of the skyrmion gas and the skyrmion lattice, but acts as a stabilizing factor against thermal fluctuations. The thermal stability was studies using Monte Carlo simulations to calculate the order parameter and the order parameter susceptibility. It is shown that for certain combinations of the external magnetic field and the Dzyaloshinskii−Moriya parameter, there is an optimal size of the structural defect that allows achieving the maximum critical temperature of the phase transition The results obtained in this study can be useful for assessing the size of the defect and the values of interaction parameters in a magnetic material with high transition temperatures in the presence of a strong planar Dzyaloshinskii−Moriya interaction.
Titanium alloys are indispensable in the aerospace, nuclear and automotive industries due to their high specific strength, excellent creep resistance and corrosion resistance, but their use is seriously limited due to poor wear resistance. The method of еlectrospark deposition using a non-localized electrode consisting of a mixture of titanium granules with the addition of 6 –12 vol.% boron carbide powder was used to obtain metalloceramic coatings Ti-TiB2 / TiC onto Ti-6Al-4V titanium alloy. The results of the study show that the coatings contain αTi, TiB, TiB2 and TiC phases. It was found that with an increase in the content of boron carbide powder in the electrode to 12 vol.%, the total ceramics concentration increases to 93 vol.%. According to the metallographic analysis data, the coating thickness varied from 43.6 to 57.6 μm. The Vickers microhardness of the coatings increased monotonically from 8.13 to 12.02 GPa with increasing ceramic concentration. The use of the developed coatings allows increasing the wear resistance of the surface of the Ti-6Al-4V titanium alloy by 48 and 71 times at loads of 25 and 50 N, respectively. The technology is proposed for applying metal-ceramic coatings to the Ti-6Al-4V alloy using B4C powder, which surpasses the corresponding laser coatings in hardness and wear resistance due to a many times higher concentration of reinforcing phases: TiB2 and TiC.