Transport through magnetic quantum point contacts

Hybrid magnetic quantum point contacts were fabricated in the plane of a two-dimensional electron gas, which is formed in a high mobility AlGaAs/GaAs quantum well structure. The hybrid gates are magnetized in an applied in-plane magnetic field and generate both magnetic fringe fields and an electrostatic confining potential. Low-temperature electrical characterization yielded well-resolved conductance plateaus and a strong 0.7-structure in the absence of an applied field. However, the well-known spin polarization effect of a quantum point contact in an applied magnetic field was absent, possibly due to suppressed electron-electron interactions.