Highlights


Professor
ElBatanouny published his new book:
Symmetry
and
Condensed Matter Physics
Links to:




 Connecting electron and phonon spectroscopy to determine quasiparticlephonon coupling
Both electron and phonon
spectrscopy can be used to yield estimates of the electronphonon
coupling parameter $\lambda$, which provides a dimensionless estimate
of the strength of the interaction in a particular material. However,
recently there has been discrepancy in reported values for the
topological insulators Bi_{2}Se_{3} / Bi_{2}Te_{3}
appearing in the literature. By employing a MatsubaraGreen's function
formalism, we have developed a technique for translating features in
phonon spectra into electronic spectral functions (see an example
below), which allows direct comparison with angle resolved
photoemission spectroscopy.
 Graphene and the Kekule mode
Graphene, a single
sheet of carbon atoms, is at the forefront of much modern condensed
matter research. Its unique electronic dispersion and incredible
structural properties make it a promising candidate for new, novel
materials. However, one of its drawbacks is its semimetal character,
with Dirac points at the K and K' points in the Brilluoin zone, which
limits its usefulness in electronics. If one could endow the charge
carriers in graphene with a finite effective mass, and thereby induce
an electronic gap, new pathways for graphene's role in modern
electronics could be opened!
 Topological Insulators Bi_{2}Se_{3} / Bi_{2}Te_{3}
These
compounds, previously known for their favorable thermoelectric
properties, have become the new star materials in the growing field of
topological
insulators. These materials exhibit conductive surface states despite
being insulators throughout their bulk. In particular Bi_{2}Se_{3} and Bi_{2}Te_{3} exhibit
surface electronic states with linear dispersion in the form of a
single Dirac Cone at the center of their surface Brillouin zone. The relatively large bandgap (~0.3 eV) in Bi_{2}Se_{3} makes
it an ideal candidate for theoretical and experimental study, as well
as potential applications in spintronics. Below you can see an image of
the rhomohedral unit cell as well as the isotropic surface Dirac cone
dispersion with arrows indicating the electronic transitions possible
as the result of scattering from phonons.
_{ }
The corrugation of the LiCuO (001) surface obtained from the
diffraction spectra:
An interesting structural transition was found on
this surface, as indicated in the animation below:
A new material found with very high
themoelectricity and superconductivity behavior.
Structure and lattice dynamics of Sr_{2}CuO_{2}Cl_{2}(001)
studied by heliumatom scattering: M. Farzaneh, X.F. Liu, M. ElBatanouny, and F. C.
Chou, Phys. Rev. B 72,
085409 (2005).
Antiferromagnetic Ordering on CoO(001) Studied by Metastable Helium Beam Diffraction: P. Banerjee, X. Liu, M. Farzaneh, C.R. Willis, W. Franzen, and M. ElBatanouny, arXiv:condmat/0401130v1.
Observation of an extraordinary
antiferromagnetic transition on the NiO(100) surface by metastable
helium atom diffraction: M.
Marynowski, W. Franzen, M. ElBatanouny, and V. Staemmler, Phys. Rev. B 60,
6053 (1999).
Frozen spinwave structure on the NiO(100)
surface observed by metastable He 2^{3}S scattering:
A. Swan, M. Marynowski, W. Franzen,
M. ElBatanouny, and K. M. Martini, Phys. Rev. Lett. 71,
1250
(1993).
