Absence of magnetic ordering in low dimensional mixed magnetic Mn-1 (-) xNixCl2 center dot H2O

作者：DeFotis G C^*; Owens T M; May W M; Boyle J H; Vos E S; Matsuyama Y; Hopkinson A T; Wallin T J; Welshhans E A

来源：Journal of Magnetism and Magnetic Materials, 2010, 322(14): 1962-1968.

DOI：10.1016/j.jmmm.2010.01.014

• Magnetic susceptibility
• Magnetization
• Hysteresis
• Random magnet
• Magnetic transition
• Exchange interaction

A new mixed magnet, Mn1-xNixCl2 center dot H2O, is examined by dc magnetization and susceptibility measurements across the entire composition range. The pure components are quasi-one-dimensional Heisenberg antiferromagnets ordering at 2.17 K (Mn) and 5.6(5) K (Ni) due to weaker interchain exchange supplementing the dominant exchange along MCl2MCl2M ... chemical and structural chains. High temperature magnetic susceptibilities yield Curie and Weiss constants in chi(M) = C/(T - theta). C(x) is linear but theta(x) displays curvature, which is analyzed to show that unlike-ion exchange is ferromagnetic and similar in size to like-ion. Most notable is the absence of antiferromagnetic susceptibility maxima down to 1.6 K from x = 0.10 to 0.95. For x = 0.05 a susceptibility maximum appears, with T-max almost 20% lower than in the pure Mn component but T-c reduced by 2%. The size of the susceptibility is enhanced by admixture, the effect of disrupted antiferromagnetic tendencies. Magnetization isotherms evolve with composition. Larger values of magnetization, under the same measuring conditions, occur for mixtures than for pure components, consistent with frustration, which weakens antiferromagnetic alignment tendencies. The competing ferromagnetic(Ni) and antiferromagnetic(Mn) intrachain interactions, along with disorder and low dimensional characteristics, presumably lead to the absence of magnetic order over a remarkably broad composition range.

• 出版日期2010-7