Compressible and incompressible stripes in a narrow electron channel

The capacitance of a single-electron wire at high quantizing magnetic fields is studied. We demonstrate that the capacitance spectroscopy allows us to study the formation of compressible and incompressible stripes directly. The electron wire is field induced in a metal insulator semiconductor heterostructure beneath a center gate. The electrostatic potential defining the wire edge is controlled by a tuning-fork-shaped electrode that encloses the center gate. It is found that the capacitance spectra are very sensitive to the wire edge potential and show a clear asymmetry of the capacitance minimum at filling factor n52. The experimental results are well described by a simple model considering the contribution of compressible and incompressible stripes in the electron channel, to the capacitance signal. The capacitance minima are thus determined in our experiments by the geometry of the compressible and incompressible stripes in the channel and not by the defect-induced density of states. @S0163-1829~96!02143-1#