Structure, magnetic and electrical transport properties of Mn 4-x Ag x N compounds

Mn(4-x)Ag(x)N compounds (x = 0.0, 0.3, 0.6, 1.0) were prepared by milling and subsequently annealing the mixture of Mn(2)N(0.86), Mn, and Ag powders. All compounds display good single-phase characteristics. Both Mn(4)N and Mn(3.7)Ag(0.3)N exhibit ferrimagnetism, and a little Ag replacement of Mn can improve the saturation magnetization. The magnetic transition of Mn(3.4)Ag(0.6)N and Mn(3)AgN below 15 K is from triangular antiferromagnetism to non-coplanar ferrimagnetism, while the ones at 256 and 275 K (Mn(3.4)Ag(0.6)N and Mn(3)AgN, respectively) have been ascribed to the gradual transition, as temperature increases, from the triangular antiferromagnetic structure Gamma(5g) to a ferrimagnetic-like one. Two minima appear on the rho(T) curves for Mn(3)AgN, with the observation of a positive magnetoresistance throughout the whole tempeature-dependent change.