UTe${}_2$: a nearly insulating half-filled $j=\frac{5}{2}$ $5f^3$ heavy fermion metal

Abstract

Correlated band theory implemented as a combination of density functional theory with exact diagonalization [DFT+U(ED)] of the Anderson impurity term with Coulomb repulsion $U$ in the open 14-orbital $5f$ shell is applied to UTe${}_2$. The small gap for $U$=0, evidence of the half-filled $j=\frac{5}{2}$ subshell of $5f^3$ uranium, 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 predicted Kondo temperature around 100 K matches the experimental values from resistivity. The electric field gradients for the two Te sites are calculated by DFT+U(ED) to differ by a factor of seven, indicating a strong site distinction, while the anisotropy factor $\eta =0.18$ is similar for all three sites. The calculated uranium moment $<M^2{>}^{1/2}$ of 3.5${\mu }_B$ is roughly consistent with the published experimental Curie-Weiss values of 2.8${\mu }_B$ and 3.3${\mu }_B$ (which are field-direction dependent), and the calculated separate spin and orbital moments are remarkably similar to Hund's rule values for an $f^3$ ion. The $U$=3 eV spectral density 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. Our results support the picture that the underlying ground state of UTe${}_2$ is that of a half-filled $j=\frac{5}{2}$ subshell with two half-filled $m_j=\pm \frac{1}{2}$ orbitals forming a narrow gap by hybridization, then driven to a conducting state by configuration mixing (spin-charge fluctuations). UTe${}_2$ displays similarities to UPt${}_3$ with its $5f$ dominated Fermi surfaces rather than a strongly localized Kondo lattice system.

14 pages, 6 figures

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Cited by in corpus (17)

• Unconventional Superconductivity in UTe2
• First Observation of de Haas-van Alphen Effect and Fermi Surfaces in Unconventional Superconductor UTe2
• Low-dimensional antiferromagnetic fluctuations in the heavy-fermion paramagnetic ladder UTe${}_2$
• Resonance from antiferromagnetic spin fluctuations for superconductivity in UTe${}_2$
• Field-induced tuning of the pairing state in a superconductor
• Quasi-2D Fermi surface in the anomalous superconductor UTe2
• Anapole superconductivity from $\mathcal{P}\mathcal{T}$-symmetric mixed-parity interband pairing
• Synchrotron Radiation Techniques and their Application to Actinide Materials
• Spin triplet superconductivity driven by finite momentum spin fluctuations
• Identifying f-electron symmetries of UTe2 with O-edge resonant inelastic X-ray scattering
• Structure of the normal state and origin of Schottky anomaly in the correlated heavy fermion superconductor UTe2
• Thermodynamic transitions and topology of spin-triplet superconductivity: Application to UTe${}_2$
• Quantifying the U $5f$ covalence and degree of localization in U intermetallics
• UTe${}_2$: a narrow band superconductor
• Slow magnetic quantum oscillations in the c-axis magnetoresistance of UTe${}_2$
• Electronic Structure of UGe${}_{2\pm x}$ Thin Films from Photoelectron Spectroscopy
• Metamagnetic transition in the two $f$ orbitals Kondo lattice model