Abstract
A double quantum well system consisting of two asymmetric In0.53Ga0.47As quantum wells, of 9 nm and 7 nm width, respectively, separated by a 4.5 nm In0.52Al0.48As barrier, has been studied using magnetotransport measurements over a wide range of different total electron densities as well as different ratios of the electron densities in the two quantum wells ns1:ns2. The Hall measurements reveal plateaus for even and odd integer filling factors , depending on the electron density. SdH and Hall measurements for an electron density ratio ns1:ns2 = 1:2 show integer filling factors = 3i (i integer). This can be understood by treating transport in both quantum wells as independent. Therefore filling factors = 1+2, with 1 and 2 filling factors of the two quantum wells, respectively, are observed. From SdH measurements other basic quantities, such as electron densities, transport and quantum lifetimes and g-factor, were obtained for both quantum wells separately. This leads to the conclusion that the upper quantum well is always less than half as populated as the lower one. It also exhibits a longer quantum lifetime and therefore shows a very pronounced g-factor enhancement, more than four times as large as for the lower quantum well. The pronounced appearance of odd filling factors is therefore understood by means of this very strong g-factor enhancement for the less populated upper quantum well for magnetic fields larger than 4 T.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call