Emergence and spectral-weight transfer of electronic states in the Hubbard ladder

Abstract

The number of electronic bands is usually considered invariant regardless of the electron density in a band picture. However, in interacting systems, the spectral-weight distribution generally changes depending on the electron density, and electronic states can even emerge or disappear as the electron density changes. Here, to clarify how electronic states emerge and become dominant as the electron density changes, the spectral function of the Hubbard ladder with strong repulsion and strong intrarung hopping is studied using the non-Abelian dynamical density-matrix renormalization-group method. A mode emerging in the low-electron-density limit gains spectral weight as the electron density increases and governs the dimer Mott physics at quarter-filling. In contrast, the antibonding band, which is dominant in the low-electron-density regime, loses spectral weight and disappears at the Mott transition at half-filling, exhibiting the momentum-shifted magnetic dispersion relation in the small-doping limit. This paper identifies the origin of the electronic states responsible for the Mott transition and brings a new perspective to electronic bands by revealing the overall nature of electronic states over a wide energy and electron-density regime.

Role of surface termination in the metal-insulator transition of V$_2$O$_3$(0001) ultrathin films

“…We also note that in figure 4(c), the integrated area within the energy ranges, 0 to -3.0 eV is enhanced by 16.5% in the AFI (108 K) phase compared to PM (300 K), indicating breakdown of 'sum rules of spectral weight' in that energy regime which in turn suggests the presence of strong correlation in the system [24,25]. Theoretically, the breakdown of 'sum rules of spectral weight' in the low-energy scale has been found in strongly correlated systems when a change of hybridization and/or electron density are introduced in the system [24,25]. A question may arise, what is the source of this extra spectral weight?…”

“…The main difference between He I α and He II α spectra is that spectral weight within the energy ranges, -5 to -8 eV decreases in the AFI phase for He I α whereas increases for He II α . The different behavior could be associated with the k z dependence of spectral weight transfer [25]. The estimated increase of spectral weight in the AFI phase within the whole measured energy ranges are ∼ 3.5% and ∼ 6% for He I α and He II α , respectively.…”

“…In general, electronic states (bands) are usually considered invariant regardless of the electron density in a band picture. However, in interacting systems, the spectral-weight distribution changes depending on the electron density, and electronic states can even emerge or disappear [24,25]. Furthermore, Kohno et al, [25], have explicitly shown that the electronic excitations much away from the Fermi level can also become dominant and exhibit significant characteristics due to the change in electron density.…”

“…However, in interacting systems, the spectral-weight distribution changes depending on the electron density, and electronic states can even emerge or disappear [24,25]. Furthermore, Kohno et al, [25], have explicitly shown that the electronic excitations much away from the Fermi level can also become dominant and exhibit significant characteristics due to the change in electron density. Keeping in mind that, as we are not externally doping carriers in the system then the total carriers should be conserved but carrier density may change across MIT due to the change in lattice volume.…”

“…However, it is not typically discussed how breaking crystal symmetry via surface termination affects the MIT and detailed systematic spectroscopic studies are barely available in the literature. In general, in strongly correlated systems, the change of hybridization, lattice volume (electron density), spin degree of freedom can show unusual spectral evolution mainly in the low-energy scale [24][25][26], however, there is still little understanding how MIT in V 2 O 3 alters the low-energy physics.…”