Nematic fluctuations and their wave vector in two-dimensional metals.

We revisit the problem of electrons on a square lattice below half-filling close to an Ising-nematic quantum critical point. For Fermi surfaces with sufficiently strong antinodal nesting, the static nematic susceptibility is maximal at the antinodal nesting wave vector within a simple random phase approximation calculation. We present a detailed analysis of the nematic susceptibility within Eliashberg theory and show that the strong interaction between fermions in the antinodal regions shifts the maximum of the nematic susceptibility to slightly larger wave vectors. The corresponding order is akin to the incommensurate charge-density wave with d-wave form factor found recently in some underdoped cuprate materials. At sufficiently high temperatures around T/t ~ 0.1, nematic fluctuations are strongest at zero wave vector. [ABSTRACT FROM AUTHOR]