Interplay between Kondo and magnetic interactions in Pr0.75Gd0.25ScGeH
Interplay between Kondo and magnetic interactions in Pr0.75Gd0.25ScGeH
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Pr0.75Gd0.25ScGeH 中近藤与磁相互作用之间的相互作用
DOI：
10.1016/j.jallcom.2023.171351
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发表时间：
2023
影响因子：
6.2
通讯作者：
Pecharsky, Vitalij K.
中科院分区：
文献类型：
--
作者：
Del Rose, Tyler;Choudhary, Renu;Mudryk, Yaroslav;Haskel, Daniel;Pathak, Arjun K.;Bhaskar, Gourab;Zaikina, Julia V.;Johnson, Duane D.;Pecharsky, Vitalij K.
结合实验和密度泛函理论（DFT）研究了pr0.75 gd0.25 scgege及其氢化物（Pr0.75Gd0.25ScGeH），揭示了这些具有明显层状结构的化合物中复杂的组成-结构-性质关系。金属间母体的氢化，结晶为四角形cessi型结构，导致各向异性体积膨胀，即晶格参数a（=b）减小，而晶格沿方向膨胀，导致细胞体积净增加。DFT计算预测了两种材料在基态时局域Gd和Pr磁矩的反平行耦合。虽然实验证实了母体化合物的这一点，但对于氢化物，没有确凿的实验证据，其中Pr矩不能降到3k。DFT结果还表明，稀土-氢相互作用降低了Pr、Gd 5态和Sc 3态在费米能的自旋极化，破坏了传导电子介导的间接交换相互作用，显著降低了磁有序温度，并在多数自旋通道中打开了伪间隙。实验和理论都表明，在没有外加磁场的情况下，氢化物具有近藤样行为，而外加磁场的增加促进了磁有序，抑制了近藤样行为。
Combined experimental and density functional theory (DFT) study of Pr0.75Gd0.25ScGe and its hydride (Pr0.75Gd0.25ScGeH) reveals intricacies of composition-structure-property relationships in those distinctly layered compounds. Hydrogenation of the intermetallic parent, crystalizing in a tetragonal CeScSi-type structure, leads to an anisotropic volume expansion, that is,a(=b) lattice parameter decreases while the lattice expands along thecdirection, yielding a net increase of cell volume. DFT calculations predict an antiparallel coupling of localized Gd and Pr magnetic moments in both materials at the ground state. While experiments corroborate this for the parent compound, there is no conclusive experimental proof for the hydride, where Pr moments do not order down to 3 K. DFT results also reveal that rare-earth – hydrogen interactions reduce spin-polarization of the Pr and Gd 5dand Sc 3dstates at the Fermi energy, disrupt indirect exchange interactions mediated by conduction electrons, dramatically reduce the magnetic ordering temperature, and open a pseudo-gap in the majority-spin channel. Both experiments and theory show evidence of Kondo-like behavior in the hydride in the absence of an applied magnetic field, whereas increasing the field promotes magnetic ordering and suppresses Kondo-like behavior.