STRIKINGLY LINEAR MAGNETIC-FIELD DEPENDENCE OF THE MAGNETORESISTIVITY IN HIGH-QUALITY 2-DIMENSIONAL ELECTRON-SYSTEMS

We report on a strikingly linear behavior of the magnetoresistivity, rho(xx) versus magnetic field B in two-dimensional electron systems at low-temperatures. While linearity of the Hall resistivity rho(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 rho(xx). The curious behavior of rho(xx) is implicitly contained in a phenomenological relationship between rho(xx) and rho(xy) proposed earlier by Chang and Tsui. Our new data on very high mobility samples dramatically confirm their conjecture of this still unresolved proportionality rho(xx) and B drho(xy)/dB.