Quantisation of hopping magnetoresistance prefactor in strongly correlated two-dimensional electron systems

Abstract

We report a universal behaviour of hopping transport in strongly interacting mesoscopic Two-dimensional Electron Systems (2DES). In a certain window of background disorder, the resistivity at low perpendicular magnetic fields follows the expected relation ρ(B_⊥) = ρ_B exp(αB²_⊥). The prefactor α_B decreases exponentially with increasing electron density but saturates to a finite value at higher densities. Strikingly, this value is found to be universal when expressed in terms of absolute resistance and and shows quantisation at R_B≈h/e² and R_B ≈ 1/2 h/e². We suggest a strongly correlated electronic phase as a possible explanation.