Spin response of hole-doped monolayer . Panel (a) [(b)] shows [] obtained for a hole sheet density (blue solid curve), (red dashed curve), and (black dot-dashed curve). Noteworthy features are the strong in-plane/out-of-plane anisotropy of the spin response, the deviations from ideal two-dimensional (2D) electron-gas behavior even for , which are getting more pronounced as the density increases, and the nonanalyticity exhibited by [] for [].
Spin-response functions in real space. To highlight deviations from the ordinary 2D electron-gas behavior, we plot the quantities in (a) [(b)] obtained for a hole density (). The red dashed (blue solid) curve shows (). The decrease of the oscillation amplitude for shows that the in-plane spin response decays faster than the power law expected for ordinary 2D electron systems. The scale factors are [5] and [1] in (a) [(b)], and .