We present a versatile design of freely suspended quantum point contacts with particular large one-dimensional subband quantization energies of up to 10meV. The nanoscale bridges embedding a two-dimensional electron system are fabricated from AlGaAs/GaAs heterostructures by electron-beam lithography and etching techniques. Narrow constrictions define quantum point contacts that are capacitively controlled via local in-plane side gates. Employing transport spectroscopy, we investigate the transition from electrostatic subbands to Landau-quantization in a perpendicular magnetic field. The large subband quantization energies allow us to utilize a wide magnetic field range and thereby observe a large exchange splitted spin-gap of the two lowest Landau-levels.
@article{arxiv.0905.3969,
title = {Magneto-electrical subbands of freely suspended quantum point contacts},
author = {C. Rossler and M. Herz and M. Bichler and S. Ludwig},
journal= {arXiv preprint arXiv:0905.3969},
year = {2010}
}