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SUMMARY:Linear and nonlinear optical dynamic responses in the Dirac semime
 tal NiTe2
DTSTART;VALUE=DATE-TIME:20260529T020000Z
DTEND;VALUE=DATE-TIME:20260529T030000Z
DTSTAMP;VALUE=DATE-TIME:20260705T182100Z
UID:indico-event-5059@indico-tdli.sjtu.edu.cn
DESCRIPTION:Speakers: Jingbo Qi (齐静波） (University of Electronic Sc
 ience and Technology of China)\n\nHost: Prof. Tao DongVenue: TDLI Meeti
 ng Room N400Tencent meeting link: https://meeting.tencent.com/dm/VazMuVKC
 0M2d  Meeting ID: 141767202\, no password Abstract:Using ultrafast opti
 cal spectroscopy\, researchers studied quasiparticle dynamics in NiTe2. Ar
 ound 60 K\, anomalous optical responses appear\, consistent with transport
  measurements. At this temperature\, a phonon-assisted electron-hole recom
 bination process shows unusual behavior\, with changes in phonon energy an
 d lifetime. These anomalies stem from a shift in the phonon mode caused by
  an abrupt modification of the electronic structure near the Fermi surface
 \, indicating emergence of Lifshitz transition. Meanwhile\, intense terahe
 rtz pulses induce nonlinear responses in this centrosymmetric material. Th
 e terahertz vector potential creates a transient effective magnetic point 
 group\, breaking symmetry and enabling second-harmonic generation—a proc
 ess beyond conventional third-order nonlinearities. This yields a signific
 ant second-order susceptibility\, confirmed by polarization-dependent sign
 als. Biography:Jingbo Qi\, a professor at the University of Electronic Sc
 ience and Technology of China. He got his Ph.D. from Vanderbilt University
  (USA). He was ever a postdoctoral associate in the National High Magnetic
  Field Laboratory and Los Alamos National Laboratory\, respectively. His m
 ain research interest focuses on using the ultrafast optical spectroscopy 
 and terahertz spectroscopy to study the dynamical properties in various sy
 stems such as topological materials and strongly correlated materials.\n\n
 https://indico-tdli.sjtu.edu.cn/event/5059/
LOCATION:Tsung-Dao Lee Institute/N4F-N400 - meeting room (Tsung-Dao Lee In
 stitute)
URL:https://indico-tdli.sjtu.edu.cn/event/5059/
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