Dual nature of 5$f$ electrons in the isostructural UM$_2$Si$_2$ family: from antiferro- to Pauli paramagnetism via hidden order
Andrea Amorese, Martin Sundermann, Brett Leedahl, Andrea Marino, Daisuke Takegami, Hlynur Gretarsson, Andrei Hloskovsky, Christoph Schlüter, Maurits W. Haverkor… 展开作者
Andrea Amorese, Martin Sundermann, Brett Leedahl, Andrea Marino, Daisuke Takegami, Hlynur Gretarsson, Andrei Hloskovsky, Christoph Schlüter, Maurits W. Haverkort, Yingkai Huang, Maria Szlawska, Dariusz Kaczorowski, Sheng Ran, M. Brian Maple, Eric D. Bauer, Andreas Leithe-Jasper, Peter Thalmeier, Liu Hao Tjeng, Andrea Severing
发表信息：
Proceedings of the National Academy of Sciences Dec 2020, 117 (48) 30220-30227
Using inelastic x-ray scattering beyond the dipole limit and hard x-ray photoelectron spectroscopy we establish the dual nature of the U $5f$ electrons in UM$_2$Si$_2$ (M = Pd, Ni, Ru, Fe), regardless of their degree of delocalization. We have observed that the compounds have in common a local atomic-like state that is well described by the U $5f^2$ configuration with the $Γ_1^{(1)}$ and $Γ_2$ quasi-doublet symmetry. The amount of the U 5$f^3$ configuration, however, varies considerably across the UM$_2$Si$_2$ series, indicating an increase of U5$f$ itineracy in going from M=Pd to Ni to Ru, and to the Fe compound. The identified electronic states explain the formation of the very large ordered magnetic moments in UPd$_2$Si$_2$ and UNi$_2$Si$_2$, the availability of orbital degrees of freedom needed for the hidden order in URu$_2$Si$_2$ to occur, as well as the appearance of Pauli paramagnetism in UFe$_2$Si$_2$. A unified and systematic picture of the U$M_2$Si$_2$ compounds may now be drawn, thereby providing suggestions for new experiments to induce hidden order and/or superconductivity in U compounds with the tetragonal body-centered ThCr$_2$Si$_2$ structure.
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