Biomedical subjects

H Buhmann

Publications and source records attributed to H Buhmann.

8 recordsLinked to original sources

PubMed2006

Direct observation of the Aharonov-Casher phase.

Ring structures fabricated from HgTe/HgCdTe quantum wells have been used to study Aharonov-Bohm type conductance oscillations as a function of Rashba spin-orbit splitting strength. We observe nonmonotonic phase changes indicating that an additional phase factor modifies the electron wave function. We associate these observations with the Aharonov-Casher effect. This is confirmed by comparison with numerical calculations of the magnetoconductance for a multichannel ring structure within the Landauer-Büttiker formalism.

Journal Article↗

PubMed2005

Thermopower of a Kondo spin-correlated quantum dot.

The thermopower of a Kondo-correlated gate-defined quantum dot is studied using a current heating technique. In the presence of spin correlations, the thermopower shows a clear deviation from the semiclassical Mott relation between thermopower and conductivity. The strong thermopower signal indicates a significant asymmetry in the spectral density of states of the Kondo resonance with respect to the Fermi energies of the reservoirs. The observed behavior can be explained within the framework of an Anderson-impurity model.

Journal Article↗

PubMed2000

Probing the potential landscape inside a two-dimensional electron Gas

We report direct observations of the scattering potentials in a two-dimensional electron gas using electron-beam diffraction experiments. The diffracting objects are local density fluctuations caused by spatial and charge-state distribution of donors in the GaAs-(Al,Ga)As heterostructures. The scatterers can be manipulated externally by sample illumination or by cooling the sample down under depleted conditions.

Journal Article↗

PubMed1995