BEGIN:VCALENDAR
VERSION:2.0
PRODID:Icfo
X-PUBLISHED-TTL:P1W
BEGIN:VEVENT
UID:6a0b03eeaf2ae
DTSTART:20201204T110000Z
SEQUENCE:0
TRANSP:OPAQUE
DTEND:20201204T120000Z
LOCATION:Online (Zoom)
SUMMARY:ICFO | ATAC IMAMOGLU
CLASS:PUBLIC
DESCRIPTION:If the Coulomb repulsion between the electrons becomes signific
 antly stronger than their kinetic energy\, the itinerant electrons in the 
 two-dimensional systems are expected to form a spatially-ordered state\, t
 ermed a&nbsp\;Wigner crystal [1]. According to former Quantum Monte Carlo 
 calculations [2]\, the ratio rs of the two energy scales must exceed 30 fo
 r such a crystallization to occur in the absence of the magnetic field (B 
 &nbsp\;= 0). Owing to severe difficulties in satisfying this condition for
  conventional semiconductors (e.g.\, GaAs)\, prior experimental studies of
  the crystalline electronic states have mainly focused on the electrons co
 nfined to single Landau level under strong external magnetic field\, which
  almost completely quenches the kinetic energy.\nIn this talk\, I will des
 cribe recent experiments in atomically-thin transition metal dichalcogenid
 es (TMDs) where it is possible to reach rs &gt\; 40. Our measurements prov
 ide a direct evidence that the electrons at densities &lt\; 3 &middot\; 10
 11 cm-2 in a pristine MoSe2 monolayer spontaneously break the continuous t
 ranslation symmetry and form a Wigner crystal even at B = 0 [3]. This is r
 evealed by our low-temperature (T = 80 mK) magneto-optical spectroscopy ex
 periments that utilize a newly developed technique allowing to unequivocal
 ly detect charge order in an electronic Mott-insulator state&nbsp\;[4]. Th
 is method relies on the modification of excitonic band structure arising d
 ue to the periodic potential experienced by the excitons interacting with 
 a crystalline electronic lattice. Under such conditions\, optically-inacti
 ve exciton states with finite momentum matching the reciprocal Wigner latt
 ice vector k&nbsp\;=&nbsp\;k&shy\;W get Bragg scattered back to the light 
 cone\, where they hybridize with the zero-momentum bright exciton states. 
 This leads to emergence of a new\, umklapp peak in the optical spectrum he
 ralding the presence of periodically-ordered electronic lattice.
DTSTAMP:20260518T121958Z
END:VEVENT
END:VCALENDAR