Hysteresis in the quantum Hall regimes in electron double quantum well structures

We present here experimental results on magnetotransport coefficients in electron double quantum well (DQW) structures. Consistent with previous studies, transport hysteresis is is observed in the electron DQWs. Furthermore, in our gated DQW samples, by varying the top layer Landau level filling (ν_top) while maintaining a relatively constant filling factor in the bottom layer (νbot), we are able to explain the sign of Rₓₓ(up)-Rₓₓ(down), where Rₓₓ(up) is the magnetoresistance when the gate voltage Vg is swept up and Rₓₓ(down) when Vg is swept down. Interestingly, at small magnetic fields hysteresis is generally stronger when the top quantum well is in the even integer quantum Hall effect (IQHE) regime (e.g., ν_top=2) than in the odd IQHE regime (e.g, ν_top=1). While at higher B fields, the hysteresis at ν_top=1 becomes the strongest. The switching occurs around the B field at νbot=3.