UTe₂: a nearly insulating half-filled j=5/2, 5f³ heavy fermion metal.

Correlated band theory implemented as a combination of
density functional theory with exact diagonalization of the Anderson
impurity model [DFT+U(ED)] is applied to UTe₂.
The small gap for U=0, is converted for U=3 eV to a flat band
semimetal with small heavy-carrier Fermi surfaces that will make properties sensitive to
pressure, magnetic field, and off-stoichiometry, as observed experimentally.
The Green's function identification gives a mass enhancement
of the order of 12 for already heavy (flat) bands,
consistent with the common heavy fermion characterization of UTe₂. The
predicted Kondo temperature around 100 K matches the experimental values.
The calculated uranium moment <M²>^1/2 of
3.5 μ_B is consistent with the experimental Curie-Weiss values.
The U=3 eV electronic structure is compared
with angle-integrated and angle-resolved photoemission spectra, with
agreement that there is strong
5f character at, and for several hundred meV below, the Fermi energy.
UTe₂ displays similarities to UPt₃ with its 5f dominated Fermi
surfaces rather than a strongly localized Kondo lattice system.