Features of the electronic structure of the ternary superconductors RRh4B4 (R = Y, Lu)

Abstract

The electronic structure and a number of thermodynamic characteristics of the ternary RRh4B4 (R = Y, Lu) systems of superconductors in the normal phase are calculated from first principles. The electronic states and interactions responsible for the superconducting and magnetic properties of these systems are analyzed. It is found that the Fermi level in the compounds YRh4B4 and LuRh4B4 is immediately adjacent to a peak in the density of electronic states and about 1 eV above a pseudogap in the electronic spectrum. The existence of a number of groups of quasi-degenerate electronic states with low effective masses near the Fermi level is revealed. These states may be the cause of a significant diamagnetic contribution of the conduction electrons to the magnetic susceptibility and may be responsible for the strong temperature dependence of the susceptibility in the rhodium borides.

Superconducting properties of the ternary boride YRh4B4

“…Because Ru substitution for Rh controls the interatomic distances between borons and between boron and Rh/Ru atoms, the density of states at Fermi energy is tuned by doping, leading to a change in T c . The electronic structure of YRh 4 B 4 has been calculated using the full potential relativistic linear muffin-tin orbital (LMTO) method considering the exchange-correlation potential in terms of the local density approximation of the density functional theory by Grechnev et al [9]. The calculation of density of states revealed that a pseudogap opens approximately 1 eV below the Fermi energy level.…”