A Mossbauer Study of Iron Impurities in the Linear Antiferromagnet TMMC

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Mossbauer measurements of TMMC (^<57>Co) have been carried out. Two different charged states, Fe^<2+> and Fe^<3+>, of iron were observed. The Mossbauer spectrum of ^<57>Fe in TMMC has been measured down to 0.3 K. Below the three dimensional transition point no magnetic h.f.s. was observed at the Fe^<2+> site. It is explained by cancellation of the Fermi contact field by the orbital and dipolar internal field. From the analysis of the Q.S. vs to T of Fe^<2> in TMMC, the following crystal field parameters were obtained: Δ=100cm^<-1>±15, λ=75±5cm^<-1>. Below 4.2 K it is necessary to introduce the exchange interaction between the Fe^<2+> and Mn^<2+> ions along the chain. A value of ∣J∣=8±1cm^<-1> was obtained within the molecular field approximation. The following Mossbauer parameters were obtained for the Fe^<2+> and Fe^<3+> ions in TMMC Fe^<2+>: Fe^<2+> IS=1.36±0.05 mm/sec., θ_D=106±20 K, Fe^<3+> IS=0.58±0.05 mm/sec., θ_D=102±25 K.
社団法人日本物理学会の論文
1974-08-15