New radical cation salt $\kappa$-(BETS)${}_2$Co${}_{0.13}$Mn${}_{0.87}$[N(CN)${}_2$]${}_3$ with two magnetic metals: synthesis, structure, conductivity and magnetic peculiarities

A new metallic radical cation salt $\kappa$-(BETS)${}_2$Co${}_{0.13}$Mn${}_{0.87}$[N(CN)${}_2$]${}_3$, where BETS is bis(ethylenedithio)tetraselenafulvalene, C${}_{10}$S${}_4$Se${}_4$H${}_8$, has been synthesized. In this salt, a part of Mn${}^{2+}$ ions are replaced by Co${}^{2+}$ which acts as a magnetic dopant with a different effective magnetic moment. Crystal structure, band structure, conducting and magnetic properties of the salt have been studied. Below 30 K the material undergoes a metal-insulator transition, which is suppressed by applying a pressure of ~0.5kbar, leading to a superconducting ground state. While the structural and conducting properties are very similar to those of the parent salt $\kappa$-(BETS)${}_2$Mn[N(CN)${}_2$]${}_3$, magnetic properties associated with localized moments in the anion layer are found to be surprisingly different.