Susceptibilite magnetique et R.P.E. du Mn2+ dans les verres du systeme : MnSGa2S3GeS2

Abstract E.P.R. and a.c. susceptibility measurements results are described. For low Mn 2+ content well resolved E.P.R. signals are observed at g = 2 (hyperfine interaction constant : A = 71.10 −4 cm −1 ) and poorly resolved signals at g = 4.3. For high Mn 2+ content the latter vanishes, and the temperature and concentration dependence of the g = 2 signal are indicative of magnetic exchange interactions. The a.c. susceptibility exhibits a cusp around 2 K (T SG ). The experiments can be interpreted by a progressive freezing of the magnetic moments, with a residual contribution of isolated Mn ++ below T SG .