Intriguing electronic and optical prospects of FCC bimetallic two-dimensional heterostructures: epsilon near-zero behaviour in UV-vis range
Higher superconducting critical temperature and large-area epsilon-near-zero systems are two long-standing goals of scientific community, having explicit relationship with chemistry of correlated electrons in localized orbitals. Motivated by the recent experimentally observed strongly correlated phenomena in nanostructures of simple Drude systems, we have theoretically investigated some potential bimetallic FCC combinations starting from large-area interface to embedded and doped two-dimensional (2D) nanostructures, having resemblance with the experimentally studied systems. Using different first-principles techniques, encompassing density functional theory (DFT), time-dependent DFT (TDDFT), phonon and DFT-coupled quantum transport, we propose the following strongly correlated prospects of potential bimetallic nanostructures like Au/Ag and Pt/Pd: 1) For 2D doped and embedded nanostructures of these systems, DFT-calculated non-trivial band-structure and Fermi-surface topology may be emblematic to the presence of instabilities like charge density waves; 2) the optical attributes extracted from the TDDFT calculations for these systems indicate interfacial morphology induced band-localization leading to near-zero behavior of both real and imaginary parts of the dynamical dielectric response in the ultra-violet to visible (UV-Vis) optical range; 3) Low-energy intra-band plasmonic oscillations, as present for individual metallic surfaces, are completely suppressed for embedded and doped nanostructures manifesting the sole responsibility of inter-band transitions, as observed from the TDDFT-derived electron-energy loss spectra; 4) Phonon-dispersion of the nanostructured systems indicates the presence of soft phonons and dynamical instabilities; 5) Quantum transport calculations on simplest possible device made out of these bimetallic systems reveal generation of highly transmitting pockets over the cross-sectional area for some selected device geometry. We envisage that, if scrutinized experimentally, such systems may unveil many fascinating aspects of orbital chemistry, physics and optics promoting relevant applications in many diverse fields.