0 A pr 1 99 6 van Hove Singularity effects in Strongly Correlated Fermions
نویسندگان
چکیده
We examine the effects of a van Hove singularity (vHs) in the density of states (DOS) of a two dimensional, t− t−U Hubbard model within the local approximation. Within our approximation the non-interacting Fermi surface is always retained away from half-filling; and we find that the vHs in the DOS survives, and for hole doping is nearly ”pinned” to the Fermi level due to the enhancement of the effective mass, m. We discuss the electron-hole asymmetry of this phenomena and its relevance to the electron and hole doped cuprates. At optimal (hole) doping, with the Fermi level at the vHs, we find that the single particle damping rate Γ, and the resistivity ρdc, scale as T for moderately low temperatures (T ∼ 100K), while for the electron doped system Γ and ρdc ∼ T .
منابع مشابه
6 J an 1 99 8 Quasiparticle Spectra in the Hubbard Model
We examine the quasiparticle lifetime and spectral weight near the Fermi surface in the two-dimensional Hubbard model. We use the FLEX approximation to self-consistently generate the Matsubara Green’s functions and then we analytically continue to the real axis to obtain the quasiparticle spectral functions. We compare the spectral functions found in the nearest neighbor hopping only Hubbard mo...
متن کاملar X iv : c on d - m at / 9 90 63 72 v 1 2 4 Ju n 19 99 Van Hove Singularity and Superconductivity in Disordered
On the basis of a simple model we analyse the influence of disorder on critical temperature TC in p–wave superconductors. The disorder is treated by means of the Coherent Potential Approximation (CPA) and we focus our attention on the effect of a van Hove singularity near Fermi energy EF . For the appropriate values of its parameters our model reproduces the experimentally found behaviour of Sr...
متن کاملVan Hove Singularity and Superconductivity in Disordered Hubbard Model
We apply the Coherent Potential Approximation (CPA) to a simple extended Hubbard model with a nearest and next nearest neighbour hopping for disordered superconductors with s–, d– and p–wave pairing. We show how the Van Hove singularities in the electron density of states enhance the transition temperature Tc for exotic superconductors in a clean and weakly disordered system. The Anderson theor...
متن کاملTunneling and Photoemission in an SO ( 6 ) Supercon - ductor
—————————————————— Combining the results of tunneling, photoemission and thermodynamic studies, the pseudogap is unambiguously demonstrated to be caused by Van Hove nesting: a splitting of the density of states peak at (π, 0). The fact that the splitting remains symmetric about the Fermi level over an extended doping range indicates that the Van Hove singularity is pinned to the Fermi level. De...
متن کامل0 Superconductivity In Disordered Sr 2 RuO
Recent experimental evidence suggests that the Cooper pairs in superconducting Sr2RuO4 are triplets with p-wave internal symmetry, as in the case of superfluid 3He1–4. One of characteristic features of this exotic state is the strong influence of impurities on its superconducting properties. Studies of the electronic structure in Sr2RuO4 2 have identified an extended van Hove singularity close ...
متن کامل