Adriana Foussats

Large-n expansion based on the Hubbard operator path integral representation and its application to the t-J model

In the present work we have developed a large-N expansion for the t-J model based on the path integral formulation for Hubbard operators. Our large-N expansion formulation contains diagrammatic rules, in which the propagators and vertex are written in term of Hubbard operators. Using our large-N formulation we have calculated, for J=0, the renormalized O( 1/N) boson propagator. We also have calculated the spin-spin and charge-charge correlation functions to leading order 1/N. We have compared our diagram technique and results with existing ones in the literature.

Large- N expansion based on the Hubbard operator path integral representation and its application to the t − J model. II. The case for finite J

We have introduced a new perturbative approach for

One-electron self-energies and spectral functions for the t − J model in the large- N limit

t-J-V

Cooperative effect of phonons and electronic correlations for superconductivity in cobaltates

model where Hubbard operators are treated as fundamental objects. Using our vertices and propagators we have developed a controllable large-N expansion to calculate different correlation functions. We have investigated charge density-density response and the phase diagram of the model. The charge correlations functions are not very sensitive to the value of

Charge order and phonon renormalizations: Possible implications for cobaltates

J

One-particle spectral properties of the t − J − V model on the triangular lattice near charge order

and they show collective peaks (or zero sound) which are more pronounced when they are well separated (in energy) from the particle-hole continuum. For a given

Self-energy effects in cuprates and the dome-shaped behavior of the superconducting critical temperature

J

Doping and temperature dependence of the pseudogap and Fermi arcs in cuprates fromd-CDW with short-range fluctuations in the context of thet-Jmodel

a Fermi liquid state is found to be stable for doping

Path integrals for dimerized quantum spin systems

\delta

Role of dynamical non-double-occupancy excitations on the quasiparticle damping of the t-J model in the large-N limit

larger than a critical doping