3D Fermi Surface of CeCoIn$_5$ from ARPES and DMFT

The three-dimensional Fermi surface (FS) of the Kondo lattice system CeCoIn$_5$ is determined using angle-resolved photoemission (ARPES) with comparison to first principles dynamical mean field theory (DMFT) calculations. Photon-, angle- and polarization-dependent ARPES mapping of the electronic structure from two orthogonal (001) and (100) cleaved surfaces reveals the deficiencies of both $f$-$itinerant$ and $f$-$localized$ density functional theory (DFT) calculations. While the well-known quasi-2D $\alpha$ sheet and the 3D $\beta$ sheet FS topologies are well described by $itinerant$ DFT, a complex $\gamma$ hole-like FS topology centered on $Z$ is newly revealed which exists only in the $localized$ DFT, and yet it hosts strong $f$ spectral weight as highlighted by Ce 4$d$-4$f$ resonant ARPES. DMFT is shown to capture the low energy scale participation of $f$ electrons in the $localized$-$like$ FS topology in agreement with ARPES, as well as reveal insights into the origins of differing effective masses of FS sheets from the complex hybridization interaction with the ground-state and first-excited CEF $f$-levels.