States induced in the single-particle spectrum by doping a Mott insulator

TL;DR

This paper investigates how doping a Mott insulator introduces new states in the single-particle spectrum, revealing a connection between magnetic excitations and electron addition spectra that reflects spin-charge separation.

Contribution

It demonstrates that in a continuous Mott transition, magnetic excitations emerge in the electron-addition spectrum with shifted dispersion, linking magnetic and electronic properties.

Findings

Magnetically excited states appear in the electron-addition spectrum during doping.

The dispersion relation shifts by the Fermi momentum in the doped Mott insulator.

Spectral weight of these states diminishes as the Mott transition is approached.

Abstract

In strongly correlated electron systems, the emergence of states in the Mott gap in the single-particle spectrum following the doping of the Mott insulator is a remarkable feature that cannot be explained in a conventional rigid-band picture. Here, based on an analysis of the quantum numbers and the overlaps of relevant states, as well as through a demonstration using the ladder and bilayer t-J models, it is shown that in a continuous Mott transition due to hole doping, the magnetically excited states of the Mott insulator generally emerge in the electron-addition spectrum with the dispersion relation shifted by the Fermi momentum in the momentum region where the lower Hubbard band is not completely filled. This implies that the dispersion relation of a free-electron-like mode in the electron-addition spectrum eventually transforms into essentially the momentum-shifted magnetic dispersion relation of the Mott insulator, while its spectral weight gradually disappears toward the Mott transition. This feature reflects the spin-charge separation of the Mott insulator.