Sign reversal of nonlocal response due to electron collisions
Electron-electron collisions are known to cause a nonlocal voltage drop in the presence of current flow. The
semiphenomenological theory predicts this drop to be opposite to the direction of the current in the ballistic
regime. We use a microscopic approach and show that the sign of this drop may be of both signs depending
on the temperature and the distance between the source and probe contacts. The change of sign corresponds to the change of the dominant scattering process from head-on collisions to backward scattering of electrons. Our results agree with the experimental data.