We show that tunnelling in the quantum Hall regime acquires the form of thermal activation above a crossover temperature T1. The width of the conductance peak oxx between Hall plateaus scales then with temperature as TK with k = 3/7 at T < T1 and crosses over to k = 6/7 at T > Tx. We find that Tl decreases for longer-range potentials or for higher magnetic fields, hence at a given temperature range the apparent k should decrease for samples with shorter-range scattering or in a given sample at higher Landau levels. These results are consistent with data showing 0.3 0.8 for different Landau levels and for the remarkable difference between In^Ga^jAs/InP and GaAs/Alj-Ga^jAs heterostructures.
ASJC Scopus subject areas
- Physics and Astronomy (all)