Atomistic simulation of FCC and HCP Ni-Gd core–shell nanosystem

This research is focused on simulations of Gd, Ni, and Ni-Gd core–shell magnetic nanosystem using VAMPIRE software and the Landau-Lifshitz-Gilbert-Heun approach. The generation of temperature dependent magnetization curves allows the estimation of the corresponding Curie temperature. Simulations at various Ni and Gd particle diameters provided critical values below which the T_c value differs from the theoretical bulk T_c value, being 5 and 7 nm for Ni and Gd, respectively. It was demonstrated that both FCC and HCP structure configurations yield undistinguishable behaviors at large particle sizes. After fitting, the values of the phenomenological shift exponent and the microscopic length of Ni and Gd corresponded to spherical nanosystem. The T_c values have been tuned by varying the core diameter of Ni-Gd core–shell nanosystem. Moreover, the antiferromagnetic coupling was seen to play a significant role in the M-T curves and spin distributions of cores and shells. The hysteresis loops produced coercivity field values driven by inter-domain coupling, as well as anisotropy decreases caused by Ni% increments and rising temperatures. These magnetic properties disclosed here are promising for future biomedical and spintronic applications.