Biomedical subjects

PE Lammert

Publications and source records attributed to PE Lammert.

9 recordsLinked to original sources

PubMed2000

Topological phases in graphitic cones

The electronic structure of graphitic cones exhibits distinctive topological features associated with the apical disclinations. Ahranov-Bohm magnetoconductance oscillations (period Phi(0)) are completely absent in rings fabricated from cones with a single pentagonal disclination. Close to the apex, the local density of states changes qualitatively, either developing a cusp which drops to zero at the Fermi energy, or forming a region of nonzero density across E(F), a local metallization of graphite.

Journal Article↗

PubMed2000

Gapping by squashing: metal-insulator and insulator-metal transitions in collapsed carbon nanotubes

Squashing brings circumferentially separated areas of a carbon nanotube into close proximity, drastically altering the low-energy electronic properties and (in some cases) reversing standard rules for metallic versus semiconducting behavior. Such a deformation mode, not requiring motion of tube ends, may be useful for devices. Uniaxial stress of a few kbar can reversibly collapse a small-radius tube, inducing a 0.1 eV gap with a very strong pressure dependence, while the collapsed state of a larger tube is stable. The low-energy electronic properties of chiral tubes are surprisingly insensitive to collapse.

Journal Article↗

PubMed1995