Electronic structures of diboride compounds: AgB2 and AuB2

Abstract

Based on electronic structure calculations, we have found that noble metal diborides, AgB2 and AuB2, are potential candidates for conventional BCS-type high-temperature superconductors. The B 2p density of states dominates at the Fermi level in comparison with the Ag 4d and the An 5d states. Furthermore, the electron-phonon coupling constant A is much larger in AgB2 and AuB2 than in MgB2. Estimated transition temperatures for AgB2 and AuB2 are T-c(cal) = 59 K and 72 K, respectively. These are about 2 similar to 3 times higher than the estimated T-c(cal) = 27 K in MgB2 and are almost comparable to those in cuprate superconductors.