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arXiv · 1901.10808

A RIXS investigation of the crystal-field splitting of Sm$^{3+}$ in SmB$_6$

Andrea Amorese·Oliver Stockert·Kurt Kummer·Nickolas B. Brookes·Dae-Jeong Kim·Zachary Fisk·Maurits W. Haverkort·Peter Thalmeier·Liu Hao Tjeng·Andrea Severing
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Abstract

The crystal-field (CF) splitting of the $^6H_{5/2}$ Hund's rule ground state of Sm$^{3+}$ in the strongly correlated topological insulator SmB$_6$ has been determined with high resolution resonant inelastic x-ray scattering (RIXS) at the Sm M$_5$ edge. The valence selectivity of RIXS allows isolating the crystal-field-split excited multiplets of the Sm$^{3+}$ (4$f^5$) configuration from those of Sm$^{2+}$ (4$f^6$) in intermediate valent SmB$_6$. The very large energy range of RIXS allows the crystal-field analysis of a high lying multiplet at about 2.4\,eV that has the same total angular momentum $J$ as the ground state so that ambiguities due to the elastic tail can be avoided. We find that the $Γ_7$ doublet and $Γ_8$ quartet of the $^6H_{5/2}$ Hund's rule ground state are split by $Δ^{CF}_{^6H_{5/2}}$\,=\,20$\pm$10\,meV which sets an upper limit for the 4$f$ band width. This indicates an extremely large mass renormalization from the band structure value, pointing out the need to consider the coefficients of fractional parentage for the hopping of the 4$f$ electrons.

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Andrea Amorese, Oliver Stockert, Kurt Kummer, Nickolas B. Brookes, Dae-Jeong Kim, Zachary Fisk, Maurits W. Haverkort, Peter Thalmeier, Liu Hao Tjeng, Andrea Severing. 2019-06-25. A RIXS investigation of the crystal-field splitting of Sm$^{3+}$ in SmB$_6$. https://doi.org/10.1103/physrevb.100.241107

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