Self-energy corrections to anisotropic Fermi surfaces

Abstract

The electron-electron interactions affect the low-energy excitations of an electronic system and induce deformations of the Fermi surface. These effects are especially important in anisotropic materials with strong correlations, such as copper-oxide superconductors or ruthenates. Here we analyze the deformations produced by electronic correlations in the Fermi surface of anisotropic two-dimensional systems, treating the regular and singular regions of the Fermi surface on the same footing. Simple analytical expressions are obtained for the corrections, based on local features of the Fermi surface. It is shown that, even for weak local interactions, the behavior of the self-energy is nontrivial, showing a momentum dependence and a self-consistent interplay with the Fermi surface topology. Results are compared to experimental observations and to other theoretical results.

Non-Fermi-liquid signatures in the Hubbard model due to van Hove singularities

“…If the singularity occurs in the vicinity of the Fermi level, strong modifications of the low-energy and temperature properties are still expected due to a pinning effect. 26,[34][35][36][37][38] In the present work we show that the non-Fermi liquid signatures which were encountered in previous studies [18][19][20][21][22][23][24][25][26][27][28][29][30][31] of the self-energy and transport properties can also occur in the paramagnetic phase of a strongly correlated metal within DMFT. We use the two-dimensional square lattice with nearest and nextnearest neighbor hopping, t and t ′ respectively.…”

“…[18][19][20][21][22][23][24][25][26][27][28][29][30][31] This should be contrasted to nested Fermi liquids, 3 where due to the nesting property of the Fermi surface the phase space volume for low-energy scattering is also strongly enhanced and unusual low-energy properties emerge as well.…”

Consistent Description of the Metallic Phase of Overdoped Cuprate Superconductors as an Anisotropic Marginal Fermi Liquid

“…First, a weak coupling treatment of the Hubbard model produces an anisotropic scattering rate of similar frequency and angular dependence. The MFL component arises from a nesting of the Fermi surface in the anti-nodal regions [32] or from proximity to a van Hove singularity [32,33]. However, for the later case the resulting scattering rate would have opposite doping dependence and would appear only at higher T than experimentaly observed for Tl2201.…”

Tight-Binding Parameters for Graphene

“…Though it was an ideal two dimensional material of theoretical interest and one of the earliest material on which tight binding band structure calculation was done 2,3 , it has triggered recently a lot of interest among people including reinvestigation of many earlier results since its experimental discovery in 2004 4 . Particularly, a large no of people have recalculated the tight binding band with nearest neighbour hopping but without overlap integral correction 1,2,3,5,6,7,8,9 , some have calculated the same by taking into account the overlap integral correction 2,8 , out of these only few calculations are there which take care of second and third nearest neighbours along with overlap integral corrections 1,9 . It is noticed that the first nearest neighbour hopping integral (γ 0 ) lies around 2.5eV-3.0eV when tight binding band is fitted with first principle calculation or experimental data 1,6,8 near the K point of the brillouin zone of graphene but interestingly, when one tries to have a good matching of the tight binding band over the whole brillouin zone by including upto third nearest neighbour hoppings and overlap integrals, the tight binding parameters are considered as merely fitting parameters, not as physical entities 1 i.e, the values of parameters do not decrease consistently as one moves towards second and third nearest neighbours.…”