Superconductivity and ferromagnetism in BM₅Se₉ (B = Al, Ga, Ge, Sn, Sb; M = V, Nb, Ta)

Abstract
An original process allows the dissolution of some intermetallic A15 phases in lamellar metallic diselenides. Thus exists a new derivative family BM₅Se₉ obtained from 2H-NbSe₂, 2H-TaSe₂ and 1T-VSe₂. In addition to the "AA-BB" or "AB-AB" stacking modes, another part played by the matrix is underlined : if it possess a metal excess, it changes the properties and leads to formation of new phases, and the entities issued from A15 dissolution determine the properties through a synergy between them and the matrix . The phases GaNb₅Se₉, SbNb₅Se₉, (Ge/Al)Nb₅Se₉, SnNb₅Se₉ and SnNb_0.5Ta_4.5Se₉ are superconductors whereas GaV₅Se₉ is ferromagnetic. Compounds presented in this work are not multi-layer systems but rather, they are hybrid and mesoscopic materials.