1. Charge fluctuations in the intermediate-valence ground state of SmCoIn$_5$
- Author
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Tam, David W., Colonna, Nicola, Kumar, Neeraj, Piamonteze, Cinthia, Alarab, Fatima, Strocov, Vladimir N., Cervellino, Antonio, Fennell, Tom, Gawryluk, Dariusz Jakub, Pomjakushina, Ekaterina, Soh, Y., and Kenzelmann, Michel
- Subjects
Condensed Matter - Strongly Correlated Electrons ,Condensed Matter - Superconductivity - Abstract
The microscopic mechanism of heavy band formation, relevant for unconventional superconductivity in CeCoIn$_5$ and other Ce-based heavy fermion materials, depends strongly on the efficiency with which $f$ electrons are delocalized from the rare earth sites and participate in a Kondo lattice. Replacing Ce$^{3+}$ ($4f^1$, $J=5/2$) with Sm$^{3+}$ ($4f^5$, $J=5/2$), we show that a combination of crystal field and on-site Coulomb repulsion causes SmCoIn$_5$ to exhibit a $\Gamma_7$ ground state similar to CeCoIn$_5$ with multiple $f$ electrons. Remarkably, we also find that with this ground state, SmCoIn$_5$ exhibits a temperature-induced valence crossover consistent with a Kondo scenario, leading to increased delocalization of $f$ holes below a temperature scale set by the crystal field, $T_v$ $\approx$ 60 K. Our result provides evidence that in the case of many $f$ electrons, the crystal field remains the most important tuning knob in controlling the efficiency of delocalization near a heavy fermion quantum critical point, and additionally clarifies that charge fluctuations play a general role in the ground state of "115" materials., Comment: 12 pages, 5 figures
- Published
- 2023
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