Mo¨ssbauer study of iron sulfides doped with 3d-transition metals

It is found by Mo¨ssbauer measurements on M_0.025Fe_0.975S (M=Sc, Ti, V, Cr, Mn, Co, Ni, Cu) that the 3d-transition metal impurities profoundly affect both the crystallographic and spin rotation transitions of iron sulfide.It is noteworthy that both V_0.025Fe_0.975S and Co_0.025Fe_0.975S have Morin transition temperatures T_M which are distinctly different from that of FeS; furthermore, the directions of changes of T_M are opposite for V_0.025Fe_0.975S and Co_0.025Fe_0.975S.A vanadium impurity of 2.5% of the metal atoms in the iron sulfide makes the crystallographic transition take place rapidly in a narrow temperature region of about 15 K, while the α transition in FeS takes place over a wide temperature range of about 200 K.It is also found that the α transition for V_0.025Fe_0.975S has a hysteresis width of 5 K.