DEPENDENCE OF INTER-EDGE-CHANNEL SCATTERING ON TEMPERATURE AND MAGNETIC-FIELD - INSIGHT INTO THE EDGE-CONFINING POTENTIAL

The inter-edge-channel equilibration length L(eq) of a high-mobility t wo-dimensional electron gas in a GaAs/AlxGa1-xAs heterostructure is st udied in the range of magnetic fields 2.8-4.5 T at temperatures of 0.5 less than or equal to T less than or equal to 11 K. The inverse of L( eq) increases with increasing T at a magnetic field (3.4 T) correspond ing to the center of the nu=4 Hall plateau, and rapidly decreases with increasing magnetic field B to depart from the center of the plateau. An analysis of these data in terms of impurity and phonon scatterings is attempted by assuming a parabolic-type confining potential. The ob served T and B dependences are consistently analyzed if the inter-edge -state spacing Delta X is assumed to be (i) much larger than the magne tic length l(B) (Delta X = 530 Angstrom, l(B) similar to 130 Angstrom) and (ii) kept nearly unchanged in the range of magnetic field studied . That the size of Delta X is nearly independent of B is an unexpected behavior, which disagrees also with recent self-consistent calculatio ns of the edge-confining potential. The validity of the assumed parabo lic-type confining potential is discussed.