Calorimetric evidence of asymmetry in the nucleation of ${\mathrm{CuMg}}_2$ in Cu/Mg multilayers

We report the observation of temperature-dependent nucleation and lateral growth behavior of the intermediate product phase ${\mathrm{CuMg}}_2$ in Cu/Mg multilayers depending if the interface is Mg on Cu or Cu on Mg. The addition of an intermediate Fe layer inhibiting ${\mathrm{CuMg}}_2$ nucleation on one of the Cu/Mg interfaces demonstrates the important role of the nature of the interface on the nucleation events of the intermediate phase. This unexpected behavior is related to the mode of growth of the thin films. A kinetic model with independent nucleation and lateral growth stages at each interface is used to fit the calorimetric curves.