Hall effect and electronic structure of La2−xSrxCuO4

Abstract

The unusual Hall coefficient ${\mathit{R}}_{\mathit{H}}$ observed in ${\mathrm{La}}_{2\mathrm{-}\mathit{x}}$ ${\mathrm{Sr}}_{\mathit{x}}$ ${\mathrm{CuO}}_4$ single crystals is explained in terms of strong electron-electron scattering in a nearly half-filled Cu ${\mathit{d}}_{\mathit{x}}^2$-${\mathit{y}}^2$ band ${\mathit{E}}_{\mathit{l}}$, together with a small number of holes in another band. Including multiple-scattering terms beyond the Born approximation yields an electron mobility that decreases dramatically as the Sr content is lowered toward x≃0.06. There, a metal-insulator transition is predicted by our analysis for an on-site Coulomb coupling U of intermediate strength. Hence the minority-hole carriers yield a net positive ${\mathit{R}}_{\mathit{H}}$ for x<0.4 by virtue of their higher mobility. Surprisingly, despite changes in ${\mathit{R}}_{\mathit{H}}$ by orders of magnitude, the calculated plasma frequency remains nearly constant with ${\mathrm{\omega }}_{\mathit{p}}$≃0.8 eV over the metallic x range, in agreement with reflectivity data.