First-principle study on electronic structures and optical properties of Au-Cu intermetallic compounds

The optical properties of Au-Cu intermetallic compounds can be tailored by varying the components, which advances their promising applications in plasmonics and optical metamaterials. However, physical insight on how components tailor the electronic structures and optical properties of those Au-Cu intermetallic compounds still lacks. In this work, first-principle study on the electronic structures and optical properties of three intermetallic compounds Au3Cu, AuCu and AuCu3 is presented. The influence of components on the electronic structure, electron-phonon coupling, dielectric function and electrical resistivity are fully investigated. The calculation of dielectric function is divided into interband and intraband part. The calculated interband dielectric function show large differences compared with that of pure Au and pure Cu, with an absorption peak emerging at low energy of around 0.3 eV. The temperature effect of intraband dielectric function is investigated by considering electron-phonon interaction. By superimposing the interband and intraband contribution, the total dielectric function of AuCu3 and AuCu shows an overall good agreement with available experimental data in literature. The calculated electron-phonon coupling strength of Au3Cu is higher than that of pure Au and Cu, whereas, the results of AuCu and AuCu3 are lower than them. In addition, the calculated electrical resistivity of all the three Au-Cu compounds are larger than that of pure Au and Cu.