Spectral Weight Transfer in Multi-Orbital Mott Systems

TL;DR

This paper introduces a formalism for multi-orbital Mott systems that reveals increased spectral weight transfer and altered symmetries, impacting low-energy theories and phenomena sensitive to particle-hole symmetry.

Contribution

It develops a general formalism for understanding spectral weight transfer in multi-orbital Mott systems, highlighting the effects of multiple orbitals on symmetries and spectral properties.

Findings

Spectral weight transfer is greatly increased in multi-orbital systems.

Particle-hole symmetry shifts from 1/3 to 1/(2n_o+1) in the atomic limit.

Dynamical contributions further increase spectral weight transfer.

Abstract

We develop here a general formalism for multi-orbital Mott systems which can be used to understand dynamical and static spectral weight transfer. We find that the spectral weight transferred from the high energy scales is greatly increased as a result of the multi-orbital structure. As a consequence certainly dynamically generated symmetries obtain at lower values of doping than in the single-band Hubbard model. For example, in the atomic limit, the particle-hole symmetric condition in the lower band shifts from the one-band result of $x=1/3$ to $x=1/(2n_o+1)$, where $n_o$ is the number of orbitals with an unpaired spin. Transport properties computed from effective low-energy theories which forbid double occupancy of bare electrons, such as the multi-orbital t-J generalization, should all be be sensitive to this particle-hole symmetric condition. Away from the atomic limit, the dynamical contributions increase the transferred spectral weight. Consequently, any phenomena which are sensitive to an emergent particle-hole symmetry should obtain at $x<(1/(2n_o+1)$.