Electronic structure and magnetism in UGa2: DFT+DMFT approach

Abstract

The debate whether uranium 5f electrons are closer to being localized or itinerant in the ferromagnetic compound UGa2 is not yet fully settled. The experimentally determined magnetic moments are large, approximately 3 Bohr magnetons, suggesting the localized character of the 5f electrons. In the same time, one can identify signs of itinerant as well as localized behavior in various spectroscopic observations. The band theory, employing local exchange-correlation functionals, is biased toward itinerant 5f states and severely underestimates the moments. Using material-specific dynamical mean-field theory (DMFT), we probe how a less approximate description of electron-electron correlations improves the picture. We present two variants of the theory: starting either from spin-restricted (LDA) or spin-polarized (LSDA) band structure. We show that the L(S)DA+DMFT method can accurately describe the magnetic moments in UGa2 as long as the exchange interaction between the uranium 6d and 5f electrons is preserved by a judicious choice of the spin-polarized double-counting correction. We discuss the computed electronic structure in relation to photoemission experiments and show how the correlations reduce the Sommerfeld coefficient of the electronic specific heat by shifting the 5f states slightly away from the Fermi level.

15 pages, 12 figures, 4 tables, added an appendix illustrating convergence with respect to Fock-space size

References in corpus (6)

• Nature of the 5f states in actinide metals
• Plane-wave based electronic structure calculations for correlated materials using dynamical mean-field theory and projected local orbitals
• An dynamical-mean-field-theory investigation of specific heat and electronic structure of $\alpha$ and $\delta$-plutonium
• Valence-band satellite in the ferromagnetic nickel: LDA+DMFT study with exact diagonalization
• Variations of magnetic properties of UGa2 under pressure
• Manifestation of electron correlation effect in $\mathrm{U}5f$ states of uranium compounds revealed by $\mathrm{U}4d-5f$ resonant photoemission spectroscopy

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• The magnetic exciton of EuS revealed by resonant inelastic x-ray scattering
• UCd${}_{11}$: A strongly localized 5$f^3$ material
• Three-dimensional flat bands and possible interlayer triplet pairing superconductivity in the alternating twisted NbSe${}_2$ moiré bulk