Resistivity Studies of Antiferromagnetic Mn-Rich Alloys Containing up to 2.5-at.% V, Cr, Fe, and Ru

In an attempt to better understand the nature of the complex magnetic interaction in antiferromagnetic $\alpha -\mathrm{M}\mathrm{n}$, we have undertaken an experimental determination of the Néel temperatures ($T_N$) of manganese-rich Mn-V, Mn-Cr, Mn-Fe, and Mn-Ru alloys. The electrical resistivities of Mn samples containing up to approximately 2.5 at.% of V, Cr, Fe, and Ru have been studied from 4.2 K to room temperature. Anomalies in the temperature dependence of the alloy resistivities at the onset of antiferromagnetic ordering reveal that dissolving V or Cr into Mn depresses $T_N$, while dissolving Fe or Ru into Mn raises the Néel temperature of the alloy. The data reveal that the introduction of impurity atoms into $\alpha -\mathrm{M}\mathrm{n}$ does not affect the antiferromagnetic coupling by a simple dilution process. $T_N$ exhibits a striking dependence on both the magnitude and sign of the excess electron concentration in the alloys.