Structure, magnetic and electrical transport properties of Mn _4-xAg_xN compounds

Mn_4-xAg_xN compounds (x = 0.0, 0.3, 0.6, 1.0) were prepared by milling and subsequently annealing the mixture of Mn ₂N_0.86, Mn, and Ag powders. All compounds display good single-phase characteristics. Both Mn₄N and Mn_3.7Ag _0.3N exhibit ferrimagnetism, and a little Ag replacement of Mn can improve the saturation magnetization. The magnetic transition of Mn _3.4Ag_0.6N and Mn₃AgN below 15 K is from triangular antiferromagnetism to non-coplanar ferrimagnetism, while the ones at 256 and 275 K (Mn_3.4Ag_0.6N and Mn₃AgN, respectively) have been ascribed to the gradual transition, as temperature increases, from the triangular antiferromagnetic structure Γ^5g to a ferrimagnetic-like one. Two minima appear on the ρ(T) curves for Mn₃AgN, with the observation of a positive magnetoresistance throughout the whole tempeature-dependent change.