Abstract Polycrystalline samples of the intermetallic compounds R2PdGe6 (R = Pr, Nd, Gd-Er) and R2PtGe6 (R = Tb, Ho, Er) have been studied using X-ray diffraction as well as magnetometric and neutron diffraction measurements. All compounds have an orthorhombic crystal structure of the Yb2PdGe6-type (space group Cmca) and are antiferromagnetic with the Neel temperatures ranging from 4.9 K for Er2PtGe6 up to 48 K for Tb2PdGe6. The magnetic properties and specific heat data collected for Nd2PdGe6 show the presence of an additional phase transition below TN at T = 4 K. Based on the neutron diffraction data, the magnetic structures have been determined for R2PdGe6 (R = Pr, Nd, Tb, Dy, Ho) and R2PtGe6 (R = Tb and Er). Both the magnetic properties and neutron diffraction data indicate that the magnetic moment is localized on rare earth atoms. The magnetic unit cell is equal to the crystal one, however, individual compounds show different types of magnetic orderings. Magnetic moments in Pr2PdGe6 form a non-collinear antiferromagnetic structure at low temperatures with magnetic moments confined to the (0 0 1) plane. The low temperature magnetic structure in Nd2PdGe6 is a collinear antiferromagnetic one with moments parallel to the b-axis and coupled ferromagnetically within the (0 0 1) plane, while along the c-axis the moments follow the + − − + sequence. With increasing temperature, a transition to a modulated magnetic structure is observed in Nd2PdGe6 at T = 4 K. The magnetic moments in R2PdGe6 (R = Tb, Dy, Ho) and Tb2PtGe6 assume a non-collinear antiferromagnetic order within the (0 0 1) plane with the + − + − sequence of signs of the moments in the neighboring planes along the c-axis. The Er moments in Er2PtGe6 form a collinear magnetic structure with magnetic moments oriented along the a-axis and coupled ferromagnetically within the (0 0 1) plane. Along the c-axis the moments follow the + − + − sequence. The magnetic structures determined here are discussed on the basis of the competition between the RKKY-type interactions and influence of Crystalline Electric Field.

中文翻译：

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R2PdGe6 (R = Pr, Nd, Gd-Er) 和 R2PtGe6 (R = Tb, Ho, Er) 的磁性和磁性结构

摘要 已经使用 X 射线衍射以及磁力和中子衍射测量研究了金属间化合物 R2PdGe6（R = Pr、Nd、Gd-Er）和 R2PtGe6（R = Tb、Ho、Er）的多晶样品。所有化合物都具有 Yb2PdGe6 型（空间群 Cmca）的正交晶体结构，并且是反铁磁性的，尼尔温度范围从 Er2PtGe6 的 4.9 K 到 Tb2PdGe6 的 48 K。为 Nd2PdGe6 收集的磁性和比热数据表明，在 T = 4 K 时，TN 以下存在额外的相变。 根据中子衍射数据，已确定 R2PdGe6 的磁结构（R = Pr、Nd、Tb、 Dy, Ho) 和 R2PtGe6 (R = Tb 和 Er)。磁性和中子衍射数据均表明磁矩集中在稀土原子上。磁性晶胞与晶体晶胞相同，但是，单个化合物显示出不同类型的磁性排序。Pr2PdGe6 中的磁矩在低温下形成非共线的反铁磁结构，磁矩限制在 (0 0 1) 平面。Nd2PdGe6 中的低温磁性结构是共线反铁磁性结构，其矩平行于 b 轴并在 (0 0 1) 平面内铁磁耦合，而沿着 c 轴，矩遵循 + - - + 序列。随着温度升高，在 Nd2PdGe6 中观察到 T = 4 K 时向调制磁结构的转变。 R2PdGe6 中的磁矩（R = Tb、Dy、Ho) 和 Tb2PtGe6 假设 (0 0 1) 平面内的非共线反铁磁顺序，沿 c 轴的相邻平面中的矩的符号为 + - + - 序列。Er2PtGe6 中的 Er 磁矩形成共线磁结构，磁矩沿 a 轴取向并在 (0 0 1) 平面内铁磁耦合。沿着 c 轴，力矩遵循 + - + - 序列。这里确定的磁结构是在 RKKY 型相互作用和晶体电场影响之间的竞争的基础上讨论的。