Neutron diffraction study of CeMn2Ge2, PrMn2Ge2 and NdMn2Ge2: evidence of dominant antiferromagnetic components within the (001) Mn planes in ferromagnetic ThCr2Si2-type manganese ternary compounds
Neutron diffraction study of CeMn2Ge2, PrMn2Ge2 and NdMn2Ge2: evidence of dominant antiferromagnetic components within the (001) Mn planes in ferromagnetic ThCr2Si2-type manganese ternary compounds
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DOI：
10.1016/0925-8388(94)01378-0
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发表时间：
1995-03
影响因子：
6.2
通讯作者：
R. Welter;G. Venturini;E. Ressouche;B. Malaman
中科院分区：
文献类型：
--
作者：
R. Welter;G. Venturini;E. Ressouche;B. Malaman
用中子衍射法重新研究了ThCr{sub2}Si{sub2}型结构RmN{sub2}Ge{sub2}(R=Ce，Pr，ND)的磁性。对先前提出的发生在锰亚晶格上的铁磁有序进行了修正。这三种化合物的特征是铁磁性和反铁磁性成分共存的混合(001)Mn面。在2-300K的温度范围内，CeMn{sub2}Ge{sub2}(T{subc}=320K)具有易轴圆锥磁结构(锥半角{α}{约}60)，在2K时总的Mn磁矩约为2.7{u}{subB}。PrMn{sub2}Ge{sub2}(T{subc}=330K)和NdMn{sub2}Ge{sub2}(T{subc}=330K)化合物具有易轴倾斜的铁磁结构({Phi}{约x}60)，而在较低的温度(T<；250K)时，Mn亚晶格({α}{约}60)呈锥形磁性结构。在PrMn{sub2}Ge{sub2}中，稀土亚晶格在100K以下具有铁磁性，在整个温度范围内，易轴占优势。在2K时，总的Mn矩约为2.8{Mu}{B}，Pr矩约为2.9{Mu}{B}。相反，在NdMn{sub2}Ge{sub2}中，易轴在250K以下向(001)面旋转，在2K时，总的Mn矩约为2.7{u}{subB}，ND矩约为2.3{u}{subB}。在所有情况下，AF分量的热依赖关系表明，在远高于居里点的温度下，没有被磁矩检测到的有序温度T{subN}发生。并与相关的RMnSi、RMnGe和RMnSi{sub2}化合物的结果进行了比较。讨论了ThCr{sub2}Si{sub2}型结构RMN{sub2}X{sub2}(X=Si，Ge)中磁性行为的演化。((原文))
The magnetic properties of ThCr{sub 2}Si{sub 2}-type structure RMn{sub 2}Ge{sub 2} (R=Ce, Pr, Nd) compounds have been reinvestigated by the use of neutron diffraction experiments. The ferromagnetic ordering previously proposed to take place on the manganese sublattice is revised. The three compounds are characterized by mixed (001) Mn planes where ferro- and antiferromagnetic components coexist. In the temperature range 2-300 K, CeMn{sub 2}Ge{sub 2} (T{sub c}=320 K) exhibits an easy axis conical magnetic structure (cone semiangle {alpha}{approx}60 ) with a total Mn moment value of about 2.7{mu}{sub B} at 2 K. Ce moments do not order above 1.6 K. At room temperature, PrMn{sub 2}Ge{sub 2} (T{sub c}=330 K) and NdMn{sub 2}Ge{sub 2} (T{sub c}=330 K) compounds exhibit an easy axis canted ferromagnetic structure ({phi}{approx}60 ) while, at lower temperature (T<250 K), a conical magnetic structure takes place on the Mn sublattice ({alpha}{approx}60 ). The rare earth sublattices orders ferromagnetically below about 100 K. In PrMn{sub 2}Ge{sub 2}, an easy axis prevails in the whole temperature range. At 2 K, the total Mn moment is about 2.8{mu}{sub B} and the Pr moment value is about 2.9{mu}{sub B}. On the contrary, in NdMn{sub 2}Ge{sub 2} the easy axis rotates to the (001) plane below 250 K. At 2 K, the total Mn moment is about 2.7{mu}{sub B} and the Nd moment value is about 2.3{mu}{sub B}. In all cases, the thermal dependence of the AF component suggests that an ordering temperature T{sub N} not detected by magnetic moments, occurs at a temperature much higher than the Curie point. The results are compared with those of the related RMnSi, RMnGe and RMnSi{sub 2} compounds. The evolution of the magnetic behaviour within the ThCr{sub 2}Si{sub 2}-type structure RMn{sub 2}X{sub 2} (X=Si, Ge) compounds is discussed. ((orig.))