Strikingly linear magnetic field dependence of the magnetoresistivity in high quality two-dimensional electron systems

We report on a strikingly linear behavior of the magnetoresistivity, ρ{variant}_xx versus magnetic field B in two-dimensional electron systems at low-temperatures. While linearity of the Hall resistivity ρ{variant}_xy versus magnetic field, punctuated in the region of the quantum Hall effect, is a direct consequence of the classical Hall geometry, there does not exist a theoretical basis for a linearity of ρ{variant}_xx. The curious behavior of ρ{variant}_xx is implicitly contained in a phenomenological relationship between ρ{variant}_xx and ρ{variant}_xy proposed earlier by Chang and Tsui. Our new data on very high mobility samples dramatically confirm their conjecture of this still unresolved proportionality between ρ{variant}_xx and B dρ{variant}_xy dB.