arXiv:1711.10835 · Physical review. B./Physical review. B
Width of the charge-transfer peak in the SU( N ) impurity Anderson model and its relevance to nonequilibrium transport
J. Fernández, Franco T. Lisandrini, P. Roura-Bas, C. J. Gazza, Armando A. Aligia
Abstract
We calculate the width $2{\mathrm{\ensuremath{\Delta}}}_{\text{CT}}$ and intensity of the charge-transfer peak (the one lying at the on-site energy ${E}_{d}$) in the impurity spectral density of states as a function of ${E}_{d}$ in the SU($N$) impurity Anderson model (IAM). We use the dynamical density-matrix renormalization group (DDMRG) and the noncrossing approximation (NCA) for $N=4$ and a 1/$N$ variational approximation in the general case. In particular, while for ${E}_{d}\ensuremath{\gg}\mathrm{\ensuremath{\Delta}}$, where $\mathrm{\ensuremath{\Delta}}$ is the resonant level half-width, ${\mathrm{\ensuremath{\Delta}}}_{\text{CT}}=\mathrm{\ensuremath{\Delta}}$ as expected in the noninteracting case, for $\ensuremath{-}{E}_{d}\ensuremath{\gg}N\mathrm{\ensuremath{\Delta}}$ one has ${\mathrm{\ensuremath{\Delta}}}_{\text{CT}}=N\mathrm{\ensuremath{\Delta}}$. In the $N=2$ case, some effects of the variation of ${\mathrm{\ensuremath{\Delta}}}_{\text{CT}}$ with ${E}_{d}$ were observed in the conductance through a quantum dot connected asymmetrically to conducting leads at finite bias [J. K\"onemann et al., Phys. Rev. B 73, 033313 (2006)]. More dramatic effects are expected in similar experiments that can be carried out in systems of two quantum dots, carbon nanotubes or other, realizing the SU(4) IAM.