CMSP Seminar @ICTP Stasi Seminar Room Wednesday 27 July at 11.00 a.m. - Davron MATRASULOV

[Condensed Matter Section]

Condensed Matter and Statistical Physics Seminar
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WEDNESDAY 27 July at 11.00 a.m.
Luigi Stasi Seminar Room, first floor, Leonardo building

Davron MATRASULOV
Turin Polytechnic University in Tashkent, Uzbekistan

Title: Supercritical Phenomena in Graphene Induced by Charged Impurities

Abstract:

Besides being a material with broad spectrum of potential nanotechnology 
application,
graphene has attracted much attention as table-top, testing ground for 
relativistic
quantum mechanics and QED in (2+1)-dimensions. The reason is caused by 
the fact
that quasiparticle dynamics in graphene is relativistic with the 
coupling constant 300-times
smaller than the fine structure constant. In particular, such 
relativistic and QED effects
as vacuum polarizaion, Schwinger pair production, Klein tunneling, 
Darmstadt effect etc.,
can be experimentally studied in graphene at almost table-top level. 
This can be achieved
by creating supercritical states in graphene via doping of graphene by 
charged impurities.
They become then planar atoms with relativistic electron dynamics. Such 
impurities can
be engineered by strain as well, or can simply result from adsorbed ions 
(as was demonstrated
by recent experiments). In this talk, discuss supercritical phenomena 
induced by two charged
(Coulomb) impurities by considering both, same and opposite (dipole) 
signs of charges by
presenting detailed introduction to relativistic quantum mechanics, 
supercritical phenomena
and the results on planar relativistic two-center Coulomb problem.

In particular, for graphene, we consider the case of two close-by impurities of equal absolute
charge. For opposite sign of the charges, this realizes a dipole potential at large distances,
while for equal charges one has a symmetric two-impurity potential. For the dipole type
impurities, we have established that the dipole potential accommodates towers of infinitely
many bound states exhibiting a universal Efimov scaling hierarchy. The dipole moment
determines the number of towers, but there is always at least one tower.__