Download Spécialité de M2 : Concepts Fondamentaux de la Physique

Master 2: International Centre for Fundamental Physics
INTERNSHIP PROPOSAL
Laboratory name: Laboratoire de Physique des Solides (LPS)
CNRS identification code: UMR 8502
Internship director’surname: Marsi
E-mail: [email protected]
Phone number: 0169155395
Web page: www.lps.u-psud.fr
Internship location: LPS – Orsay – Université Paris-Sud
Thesis possibility after internship:
Funding: YES
YES
If YES, which type of funding: Ecole Doctorale
Ultrafast study of Dirac fermions in Topological Insulators
The recent discovery of the spin quantum Hall effect has triggered an intense worldwide interest in
a new class of materials called topological insulators. These materials are characterized by
conducting, gapless surface states, while their bulk is insulating. In these materials, the
topologically protected surface states can be described by the Dirac equation: they are constituted
by massless Dirac fermions like in graphene, but with an additional chiral texture in their electron
spin distribution.
One of the most exciting opportunities is the combined use of these materials and femtosecond
lasers (Fig. 1) to develop ultrafast topological devices. In particular, when ultrafast lasers are used
in pump-probe combination with an Angle Resolved PhotoElectron Spectroscopy (ARPES) setup,
a time-resolved study of the evolution of the electronic bands of matter can be performed with fs
time resolution.
Fig. 1: laser setup for ultrafast studies
Fig. 2: Dirac cone in a topological insulator
A fellowship is available for a doctoral thesis on this topic at the Université de Paris-Sud on the
application of this new and powerful experimental technique (time-resolved ARPES) to the study
of photoexcited Topological Insulators. The main points that will be investigated are the empty
electronic states, their lifetime and recombination mechanisms, and in general all the phenomena
that drive the relaxation of hot Dirac fermions in these systems (Fig. 2).
Please, indicate which speciality(ies) seem(s) to be more adapted to the subject:
Condensed Matter Physics: YES
Quantum Physics:
YES
Macroscopic Physics and complexity: NO
Theoretical Physics:
NO