A study of the Neel transition and the Kondo-like effect of γ-Fe-Mn-Si alloys

The temperature (T) dependences of the magnetic susceptibility, chi , electrical resistivity, rho , and elastic modulus, E, of gamma -Fe-31 at.% Mn alloys containing 2.04, 5.33 and 8.71 at.% Si were examined. The Neel transition accompanied by an anomalous change of rho and E has been found in these alloys. With increasing Si content, the Neel temperature T N decreases; for T>T N , the magnetic state of the alloys transforms from Pauli paramagnetism to a paramagnetic state obeying the Curie-Weiss law, and the anomalous resistivity increases rapidly to present a negative temperature coefficient below T N . In lowering the temperature 4.2 K, no second resistivity anomaly for gamma -Fe-31 at.% Mn alloy was found, but a secondary resistivity minimum was observed at about 34 K in the gamma -Fe-31 at.% Mn-5.3 at.% Si alloy. It appears to be due to the Kondo-like effect. This leads the author to assume that both the formation of a localised net magnetic moment on Fe atoms and the transition from incommensurate to commensurate spin-density-wave state are caused by an addition of Si to gamma -Fe-Mn alloys.