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本文研究Al,Si及Cr对反铁磁性γ-Fe-Mn基合金的Neel转变及电阻极小的影响.结果表明,Cr对Fe-Mn基合金的磁化率(X),X-T及ρ(电阻率)-T关系的影响较小,也不促进基体形成局域净磁矩.相反,Al,Si则显著改变γ-Fe-Mn合金的磁结构、X-T及ρ-T关系,在Neel温度T_N以下,随反铁磁转变的磁性电阻ρ_m的增大,出现电阻极小,随后出现负电阻温度系数.降温直至4.3k,γ-Fe-Mn及γ-Fe-Mn-Cr合金在试验精度内未呈现任何电阻反常变化,而固溶Al或Si后则观察到第二次电阻极小,电阻极小温度T_(min)~(2)与电阻极小深度△ρ(ρ_(4k)～ρ_(T_(min)))随Al,Si浓度的增大而增加,且在T_(min)~(2)—4k间,ρ随lgT的降低而线性增大.由此可以假定,反铁磁态γ-Fe-Mn中加入Al或Si,导致Fe离子处形成局域净磁矩,并发生ISDW-CSDW态转变,因而产生类似Kondo效应的低温电阻极小.

The effect of Al, Si and Cr on the temperature dependence of susceptibility, X, and resistivity, ρ, of γ-Fe-Mn (23.8-31.6at.-%) alloys containing Al, Si and Cr has been investigated over the temperature range of 77-750K and 4.3-48GK. respectively. The Cr was detected to be slightly influenced upon their x and X-T or ρ-T. And it does not enable the matrix to form a localized net moment associated with Fe atoms. While the addition of certain amount of Al or Si may remarkably modify the magnetic structure as well as the temperature dependence of X or ρ. With the increase of antiferromagnetic transition resistivity below the Neel temperature, a resistivity minimum appears and then present a negative tem- perature coefficient. Down to 4.3 K, neither anomaly for resistivity of γ-Fe-Mn and γ-Fe-Mn-Cr alloys was found within experimental accuracy, but the secondary resistivity minimum was observed in γ-Fe-Mn alloys containing Al or Si. The temperature of minimum T_(min)~(2), and the depth of minimum △ρ(ρ_(4k)—ρ_r_(min)~(2)) of resistivity increase with the increase of concentration of Al or Si. The resistivity increases linearly with the decrease of lgT between T_(min)~(2) and 4K. It seems to be proposed that the formation of a localized magnetic net moment on Fe atoms and the transition from the incommensurate SDW state to commensurate SDW one are caused by the resistivity minimum in antiferromagnetic γ-Fe-Mn alloys with an addition of Al or Si, thus the low temperature resistivity minimum is due to the Rondo-like effect.