Interface effects on heat dynamics in embedded metal nanoparticles during swift heavy ion irradiation

Swift heavy ion (SHI)-induced shape modification of metal nanoparticles (NPs) embedded in an insulating matrix has been reported in many experimental studies. The shaping process was studied theoretically by modeling transport of the heat generated by electron excitations during a SHI impact on the embedded NP. These models have assumed that the interface between the matrix and the metal does not alter the heat flow. However, the difference between the Fermi level of the metal and the bottom of the conduction band in the insulator may result in a significant energy barrier that obstructs the free flow of the heat carried by energetic electrons. Moreover, the interface may enhance electron-lattice scattering and resist lattice heat conduction. In this work, we use the finite-element method to solve partial differential equations for heat conduction through the interface between the metal NP and the insulating matrix including interface effects. Based on an exemplary case of a gold NP embedded in a silica matrix, we study how the processes at the interface may alter the heat transport through it. We observe that obstruction at the interface impacts mainly the timescale and efficiency of material melting. Each of the studied effects changes the size and shape of the NP regions, where the temperature rises above the melting point. Understanding the role of the interface on heat dynamics during SHI impacts can improve estimations of the maximal size of embedded NPs that are still susceptible to shape modification by energetic ions. The accuracy of model predictions can be crucial for the development of nanoscale optoelectronic applications.