Physical properties of spinel-type superconductors CuRh2S4 and CuRh2Se4: A DFT study

Abstract

The structural, elastic, electronic, Vickers-Hardness, vibrational, Optical and thermodynamical properties of potentially technologically significant superconductors CuRh2S4 and CuRh2Se4 have calculated using density functional theory (DFT) with CASTEP code. The calculated lattice parameters and other properties have compared with available experimental values and found good agreement with them. The mechanical stability found for CuRh2S4 and CuRh2Se4 under Born stability conditions. Pugh’s ratio indicates the both are ductile and Poisson’s ratio reveals the brittle nature. The valence band and conduction bands overlapped each other at the Fermi level indicates the metallic nature of CuRh2S4 and CuRh2Se4. The density of states shows that S-3p and Se-4p states are more effective at the Fermi level. The charge density difference maps indicates the Cu-Rh bonds are stronger than Cu-S. The chemical bonding shows a combination of ionic, covalent and metallic nature for CuRh2S4 and CuRh2Se4. The Vickers-Hardness indicates the soft material with comparing to Diamond and suitable to use wires and ribbon cables. The electron- and hole-like sheets make the complex multisheet Fermi surface of CuRh2S4. The different optical functions are also observed clearly. The absorption spectra indicate that CuRh2S4 is more suitable to use in solar cell rather than CuRh2Se4. The reflectivity spectrum indicates that these compounds are promising candidate for reflector material. Debye temperature indicates that CuRh2S4 and CuRh2Se4 should have advantages to use as a thermal barrier coating (TBC) material. The electron-phonon coupling constant indicates the phonon-mediated medium coupled BCS superconductors. The obtained potential results in present calculation could provide a significant movement for future studies. Keywords: Elastic properties, Bonding analysis and Vickers hardness, Optical properties, Vibrational properties and electron-phonon coupling constant