arXiv subjects
Publications and source records attributed to P. N. Butcher.
We explain for the first time thermopower data for p-type GaAs/AlGaAs layers. The data span a temperature range between 0.2 to 1.2K. We calculate both the diffusion $S^{d}$ and the phonon-drag $S^{g}$ contributions to the thermopower. We find that $S^{d}$ is significant for temperatures up to 0.3K while at higher temperatures $S^{g}$ dominates. The calculated and measured $S^{g}$ agree very well with no adjustable parameters.
With a model calculation, we demonstrate that a non-invasive measurement of intrinsic quantum Hall effect defined by the local chemical potential in a ballistic quantum wire can be achieved with the aid of a pair of voltage leads which are separated by potential barriers from the wire. Büttiker's formula is used to determine the chemical potential being measured and is shown to reduce exactly to the local chemical potential in the limit of strong potential confinement in the voltage leads. Conditions for quantisation of Hall resistance and measuring local chemical potential are given.