Carsten Honerkamp

Ultracold fermions and the SU(N) Hubbard model.

We investigate the fermionic SU(N) Hubbard model on the two-dimensional square lattice for weak to moderate interactions using renormalization group and mean-field methods. For the repulsive case U>0 at half filling and small N the dominant tendency is towards breaking of the SU(N) symmetry. For N>6 staggered flux order takes over as the dominant instability, in agreement with the large-N limit. Away from half filling for N=3 two flavors remain half filled by cannibalizing the third flavor. For U<0 and odd N a full Fermi surface coexists with a superconductor. These results may be relevant to future experiments with cold fermionic atoms in optical lattices.

Instabilities of interacting electrons on the triangular lattice

Motivated by the recent finding of superconductivity in layered

Staggered Flux Vortices and the Superconducting Transition in the Layered Cuprates

{mathrm{CoO}}_{2}

Flow of the quasiparticle weight in the N -patch renormalization group scheme

compounds, we investigate superconducting and magnetic instabilities of interacting electrons on the two-dimensional triangular lattice. Using a one-loop renormalization-group scheme for weak- to moderate-coupling strengths, we find that for purely local interactions

Cuprates and Ruthenates: Similarities and Differences

Ug0

Single band model for the unconventional superconductivity in both cuprates and ruthenates

and small Fermi surfaces the renormalization-group flow remains bounded down to very low scales and no superconducting or other instabilities can be detected. Antiferromagnetic exchange interactions J generate a wide density region with a

Staggered flux fluctuations and the quasiparticle scattering rate in the SU(2) gauge theory of the t-J model.

{d}_{{x}^{2}ensuremath{-}{y}^{2}}{+id}_{mathrm{xy}}ensuremath{-}mathrm{w}mathrm{a}mathrm{v}mathrm{e}

Ferromagnetism and triplet superconductivity in the two-dimensional Hubbard model

superconducting instability similar to recent proposals for the strongly correlated

Renormalization group study of the Hubbard model at the van Hove singular point

tensuremath{-}J

Breakdown of the Landau-Fermi liquid in two dimensions due to umklapp scattering

model. For larger Fermi-surface volumes the interactions flow to strong coupling also for purely local interactions