Strong effect of magnetism at the cobalt-magnesium solid-liquid interface

We studied atomic structure of Mg melts at the interface with ferromagnetic Co using first-principles molecular dynamics simulations. The exchange interaction between Co and Mg is weak with an induced interfacial Mg moment of only approximately 0.02 μ_B per Mg atom. Nonetheless, magnetism substantially modifies the structure of the solid-liquid interface, with the solid-liquid interfacial distance increasing by 10 %. Magnetism reduces the ordering of the liquid layers while altering their dynamical properties, which may influence interfacial behaviours relevant to nucleation. Additionally, the magnetism of the Co substrate leads to greater energy differences and reduces electron transfer across the interface. These findings offer valuable insights into the role of magnetism at heterogeneous solid-liquid interfaces, advancing our understanding of the intricate interplay between magnetic and electronic effects during solidification.