Phonon thermal transport in alloyed and hybrid zigzag nanoribbons of gold and silver

Abstract

We have investigated phonon transport in alloyed (Au_0.5Ag_0.5) and hybrid (Au_mAg_n; here <em>m</em> and <em>n</em> are indices for the width of respective nanoribbons) zigzag nanoribbons of gold and silver. To this endeavour, we have employed the non-equilibrium Green’s function approach integrated with force-field methods as implemented in the General Utility Lattice Program. The phonon thermal conductance <em>k_ph</em> has been computed and its dependence on width of nanoribbons and temperature has been explored. It has been found that <em>k_ph</em> increases linearly with the width for the alloyed nanoribbons. However, the hybrid nanoribbons exhibit the linear behavior only for the special case of <em>m</em>=<em>n</em>. The calculated results of <em>k_ph</em> are compared with the corresponding pristine nanoribbons. Interestingly, we find that both alloying and hybridization result in a significant reduction in <em>k_ph</em>. For a comparable width, the reduction is more in the alloyed nanoribbons. Thus, our study suggests that alloying may be exploited to suppress the phononic thermal conductance, and hence to enhance the thermoelectric efficiency of nanoribbons.