Seminars Archive
Alexei Fedorov
Abstract
Tuesday, May 16, 2000, 11:00
Seminar Room, ground floor, Building "T"
Sincrotrone Trieste, Basovizza
I.D. required for external visitors
Photoemission studies of layered dichalcogenide 2H-TaSe2 in the normal
and Charge Density Wave states
Alexei Fedorov
(Brookhaven National Laboratory, Upton, NY)
ABSTRACT
Coupling of electrons to collective modes such as phonons or magnons
is known to produce corrections to the free-electron like dispersion in
the vicinity of the Fermi energy. Modifications occur in a range on the
order of the energy of the collective mode, e.g. the Debye energy in the
case of phonons. The perturbation is manifested in an enhancement
of the electron effective mass. In the present study we examine the possibility
of observing the interaction of electrons with excitations other than phonons.
We have performed a high energy and momentum resolved ARPES study of the
layered compound 2H-TaSe2 at temperatures above and below the Charge Density
Wave(CDW) transition which in this material can coexist with the superconductivity.
At temperatures well below the critical temperature for the CDW transition
we detect strong renormalization of the band dispersion which together
with a change in the ARPES line shapes suggests possible coupling of electrons
to a collective excitation with energy of the order of 100 to 150 meV.
As a two-dimensional correlated system 2H-TaSe2 represents an interesting
material for comparison with the high-Tc superconducting materials. The
different models which have been put forth to explain the Charge Density
Wave transition in this material will also be addressed.
