Doped Mott Insulator as the Origin of Heavy-Fermion Behavior in ${\mathrm{LiV}}_2{\mathrm{O}}_4$

We investigate the electronic structure of ${\mathrm{LiV}}_2{\mathrm{O}}_4$, for which heavy-fermion behavior has been observed in various experiments, by the combination of the local density approximation and dynamical mean field theory. To obtain results at zero temperature, we employ the projective quantum Monte Carlo method as an impurity solver. Our results show that the strongly correlated $a_{1g}$ band is a lightly doped Mott insulator which, at low temperatures, shows a sharp (heavy) quasiparticle peak just above the Fermi level, which is consistent with recent photoemission experiments by Shimoyamada et al. [Phys. Rev. Lett. 96, 026403 (2006)].

Figure 1

Left panel: Band dispersion of the effective 2-orbital model (solid line) and total band structure (dashed line) of ${\mathrm{LiV}}_2{\mathrm{O}}_4$. Right panel: partial $a_{1g}$ and $e_g^{\pi }$ DOS for the model. $E_F$ is set to zero.

Figure 2

Spectral function of ${\mathrm{LiV}}_2{\mathrm{O}}_4$ at $\beta =10$, 20, and $40{\mathrm{eV}}^{-1}$ ($T\approx 1200$, 600, and 300 K); $U=3.6$, $U^{\prime }=2.4$, and $J=0.6$ (all units are in eV). The insets show a close-up view immediately above $E_F$ ($\omega =0$).

Figure 3

Same as Fig. 2 but now at $T=0$ (PQMC), compared to $\beta =40{\mathrm{eV}}^{-1}$ corresponding to $T\approx 300\mathrm{K}$. In agreement with experiment, we can see a sharp peak slightly above $E_F$ (set to zero) in the $a_{1g}$ band.

Figure 4

Green function for the $a_{1g}$ (a) and $e_g^{\pi }$ (b) orbitals obtained by $\mathrm{LDA}+\mathrm{DMFT}(\mathrm{PQMC})$ as a function of $\tau$, compared with the result for $\beta =40{\mathrm{eV}}^{-1}$ ($T\approx 300\mathrm{K}$). In the inset, we magnify the region $\tau >1$.

Figure 5

Spectrum (top) and Green function (bottom) of the $a_{1g}$ band without $a_{1g}\mathrm{\text{−}}{e}_g^{\pi }$ hybridization. The sharp peak above $E_F$ survives if the hybridization is switched off.