The BM5Se9 phases: studies of the behaviour of superconductors and ferromagnets

摘要: Syntheses performed in the A 3 B/MSe 2 systems lead to formation of (B/B')(M/A) 5 Se 9 phases (ferromagnets or superconductors) {A=M= (Nb, V, Ta); B=B'= (Al, Ge, Ga, Sn, Sb)}. The magnetic studies on GaV , 0.15 Ta 4.85 and Sn 0.94 Ga 0.05 V 0.30 Nb 4.70 compared that SnNb GaNb show presence modifies superconducting exchanges allows ferromagnetic couplings. Through Point-Contact Spectroscopy it is shown nanoclusters pristine NbSe exist, so properties result from a synergy between them matrix, could be mesoscopic superconductor. superconductors' s T c values vary 17.5(2) K for 6.0(2) SbNb state transition 22K 35 . 119 121 Sb Mossbauer are obtained itself; this last one, types sites corresponding species were observed with reversible dynamic process SnII Sn-Se correlated modification Sn-Nb site(1). at K, shows just singlet, attributed surrounded by ; 298 presents one asymmetrical site without any transferred field an increased asymmetry when decreases. weak complicated ferromagnet. In both cases, ESR spectrum 300 can fitted lorentzian distributions: first case, axial symmetries, second only remains symmetry, belonging sites. its vanadium thus less symmetrical than case.