T_c Maximum in Solid Solution of Pyrite IrSe_2-RhSe_2 Induced by Destabilization of Anion Dimers

摘要

We have established a well-defined dome-shaped T_c curve in Ir_(0.94-x)JRk_xSe_2 superconductors. The maximum T_c(onset) of 9.6 K was obtained at x = 0.36, at which the Se-Se separation in the dimer anion is the longest. Simultaneously, the destabilization of Se-Se dimers accompanied by partial electron transfer from the Ir/Rh to the chalcogenide ions resulted in the emergence of optimal T_c.