Spectral weight transfer in multiorbital Mott systems

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/(2no + 1), where no 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/(2no + 1).

Orbital polaron in double-exchange ferromagnets

“…15,16 Our numerical results of the characteristic three-peak structure confirm the analytical predictions of Lee and Philips for the complete model including the double hopping term. 17 We interpret the narrow quasiparticle peak as an orbital polaron that was known before in the field of manganites. 11 These former studies considered the one-hole problem in the effective, low-energy, t-J like Hamiltonian.…”

“…The spectral weight transfer we observe between n = 1 − x and n = 2 + x is also in good agreement with earlier published analytic results. 17 The narrow peaks at the Fermi energy we observe in Fig. 2 are both quasiparticle peaks, we will discuss this in Sec.…”

“…For n = 1 ± x or n = 2 ± x we can compare our results to those obtained in a recent paper by W.-C. Lee and P. W. Philips. 17 Around n = 1 one clearly finds the series of three consecutive upper Hubbard bands, with the spectral weight distribution 3:2:1 (see Fig. 2).…”

“…It leads to characteristic features in the unoccupied parts of the spectral function confirming the analytical results of Lee and Phillips. 17 The paper is set up as follows. After introducing the double-exchange Hubbard model and the numerical method (Secs.…”

Characterizing featureless Mott insulating state by quasiparticle interference: A dynamical mean field theory view

“…This feature is correct in the atomic limit of the Hubbard model 7 , but in general the electron self energy should depend on the momentum whenever t/U is non-zero. Nevertheless, since we are mainly interested in the Mott insulating state in which t/U is a small parameter, the momentum-dependence of the electron self energy should be very weak in the Mott insulating state, which has been discussed in previous studies [31][32][33][34][35][36] . As a result, the predicted re-entry of the non-interacting QPIs at a critical bias voltage should be robust even as the momentum dependence of the electron self energy is considered.…”