Magnetization of a Bilayer 2d Electron Gas

Abstract

We present torque-magnetometry measurements of a bilayer two-dimensional electron gas (2DEG) with an inter-well barrier thin enough to enable a strong coupling between the quantum wells. We observe magnetization steps related to symmetric-anti-symmetric (SAS) transitions. Increasing the in-plane magnetic field leads to a reduction of the SAS splitting. Surprisingly, the heights of the magnetization steps related to Landau-level transitions are reduced relative to those measured for single-layer 2DEGs, suggesting that an in-plane magnetization component plays a role. Finally, at total filling factor v = 4, we observe an unidentified magnetization peak superposed upon the Landau-level step.

Destruction of Correlated Bilayer States Subjected to Tilted Magnetic Fields

“…Please note that each level consists of two spin-split sub-levels, a splitting which is too small to be visible in the figure . A consequence of the Landau quantization is the occurrence of minima in the resistivity p xx as visualized for our sample in Tilting the sample in a magnetic field adds an additional in-plane field to the system. This leads to a decrease of the interlayer coupling, and, therefore, to a reduction of ASAS-2 ' 1,9 Additionally, the spin-splitting, proportional to the total field, increases. As a consequence, the v = 6 and v = 10 quantum Hall states weaken with increasing tilt angle, because they are associated to the gap between the energetically higher lying spin level of a symmetric state and the energetically lower lying spin level of an antisymmetric state.…”