Biomedical subjects

J Schliemann

Publications and source records attributed to J Schliemann.

3 recordsLinked to original sources

PubMed2001

2D bands and electron-phonon interactions in polyacene plastic transistors.

We present a simple tight-binding model for the two-dimensional energy bands of polyacene field-effect transistors and for the coupling of these bands to lattice vibrations of their host molecular crystal. We argue that the strongest electron-phonon interactions in these systems originate from the dependence of intermolecule hopping amplitudes on collective molecular motion, and introduce a generalized Su-Schrieffer-Heeger model and is parameter-free once the band mass has been specified. We compute alpha(2)F(omega) as a function of two-dimensional hole density, and are able to explain the onset of superconductivity near 2D carrier density n(2D) approximately 10(14) cm(-2), observed in recent experiments.

Journal Article↗

PubMed2001

Strong correlation to weak correlation phase transition in bilayer quantum Hall systems.

At small layer separations, the ground state of a nu = 1 bilayer quantum Hall system exhibits spontaneous interlayer phase coherence. The evolution of this state with increasing layer separation d has been a matter of controversy. We report on small system exact diagonalization calculations which suggest that a single-phase transition, likely of first order, separates incompressible states with strong interlayer correlations from compressible states with weak interlayer correlations. We find a dependence of the phase boundary on d and interlayer tunneling amplitude that is in very good agreement with recent experiments.

Journal Article↗

PubMed2000

Bilayer quantum hall systems at filling factor nu = 2: An exact diagonalization study

We present an exact diagonalization study of bilayer quantum Hall systems at filling factor nu = 2 in the spherical geometry. We find the high-Zeeman-coupling phase boundary of the broken symmetry canted antiferromagnet is given exactly by previous Hartree-Fock mean-field theories, but that the state's stability at weak Zeeman coupling has been qualitatively overestimated. In the absence of interlayer tunneling, degeneracies occur between total spin multiplets due to the Hamiltonian's invariance under independent spin rotations in top and bottom two-dimensional electron layers.

Journal Article↗