Orientation of ground-state orbital in CeCoIn${}_5$ and CeRhIn${}_5$

Abstract

We present core level non-resonant inelastic x-ray scattering (NIXS) data of the heavy fermion compounds CeCoIn${}_5$ and CeRhIn${}_5$ measured at the Ce $N_{4,5}$-edges. The higher than dipole transitions in NIXS allow determining the orientation of the ${\Gamma }_7$ crystal-field ground-state orbital within the unit cell. The crystal-field parameters of the Ce$M$In${}_5$ compounds and related substitution phase diagrams have been investigated in great detail in the past; however, whether the ground-state wavefunction is the ${\Gamma }_7^{+}$ ($x^2-y^2$) or ${\Gamma }_7^{-}$ ($xy$ orientation) remained undetermined. We show that the ${\Gamma }_7^{-}$ doublet with lobes along the (110) direction forms the ground state in CeCoIn${}_5$ and CeRhIn${}_5$. For CeCoIn${}_5$, however, we find also some contribution of the first excited state crystal-field state in the ground state due to the stronger hybridization of 4$f$ and conduction electrons, suggesting a smaller ${\alpha }^2$ value than originally anticipated from x-ray absorption. A comparison is made to the results of existing density functional theory plus dynamical mean-field theory calculations.

6 pages, 4 figures

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• 4$f$ crystal field ground state of the strongly correlated topological insulator SmB${}_6$
• Determining the in-plane orientation of the ground-state orbital of CeCu2Si2
• Structural investigations of CeIrIn${}_5$ and CeCoIn${}_5$ on macroscopic and atomic length scales
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Cited by in corpus (9)

• Spectroscopic evidence of Kondo-induced quasi-quartet in CeRh${}_2$As${}_2$
• Possible multi-orbital ground state in CeCu${}_2$Si${}_2$
• Spectroscopic Evidence for the Direct Involvement of Local Moments in the Pairing Process of the Heavy-Fermion Superconductor CeCoIn${}_5$
• Hyperfine Couplings as a Probe of Orbital Anisotropy in Heavy Fermion Materials
• Photoemission signature of momentum-dependent hybridization in CeCoIn${}_5$
• Charge fluctuations in the intermediate-valence ground state of SmCoIn${}_5$
• Anisotropic excitonic magnetism from discrete ${\mathrm{C}}_4$ symmetry in CeRhIn${}_5$
• Square skyrmion lattice in multiorbital $f$-electron systems
• Effects of crystal field and momentum-based frustrated exchange interactions on multiorbital square skyrmion lattice