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X-WR-CALNAME:LASSP & AEP Seminar: Mengkun Liu (Stony Brook)
X-WR-TIMEZONE:Eastern Time (US & Canada)
BEGIN:VEVENT
DTSTAMP:20261017T130806Z
UID:tag:localist.com\,2008:EventInstance_47632331621303
DTSTART:20241105T172000Z
DTEND:20241105T182000Z
DESCRIPTION:Landau level Nanoscopy of charge and heat transport in Dirac he
 terostructures\n\nIn contemporary condensed matter physics and photonics\,
  four key length scales play an essential role in shaping the behavior of 
 quantum materials: (1) the polaritonic wavelength (λ) in the infrared (IR
 ) and terahertz (THz) frequency range\, which governs light confinement an
 d light-matter interactions\; 2) the magnetic lengths l_B =√(ℏ/eB)=257
 Å/√(B[T]) determined by the magnetic field B\, which constrains electr
 on motion\; 3) the diffusion length D of the hot carriers at interfaces an
 d the edges\, which dictates energy relaxation\, and 4) the periodicities 
 of superlattices induced by moiré engineering\, which defines the energy 
 scale of emerging quantum phases. For instance\, the commensurability of t
 he magnetic lengths (e.g. ~10 nm for graphene at 7T) and superlattice cons
 tant (e.g. ~10 nm for twisted bilayer graphene at ‘magic angle’) would
  give rise to exotic fractal quantum states. In this talk\, I will present
 : 1) A cutting-edge optical spectroscopy technique\, Landau-level nanoscop
 y\, capable of simultaneously probing all four critical length scales in a
  single experiment\; 2) the discovery of a new class of infrared polariton
 s that can be tuned by magnetic fields\, enhancing our ability to manipula
 te light-matter interactions and probe many-body physics at the nanoscale\
 ; 3) nanoscale mapping of thermoelectric properties in low-dimensional ele
 ctron systems within the quantum Hall regime\, revealing strong violations
  of the Wiedemann-Franz law. Our approach establishes Landau-level nanosco
 py as a versatile platform for investigating magneto-optical effects and m
 any-body interactions with unprecedented spatial resolutions. Our prelimin
 ary results also set the stage for future spectroscopic explorations of to
 pological and chiral photonic phenomena in complex quantum materials using
  low-energy photons.\n \n\nBio:\nMengkun Liu earned his Ph.D. from Boston 
 University\, where he worked with Prof. Richard D. Averitt. He later joine
 d Prof. D. N. Basov's lab at UC San Diego and was appointed as an assistan
 t professor in the Department of Physics and Astronomy at Stony Brook Univ
 ersity in 2015. He currently holds a joint appointment at Brookhaven Natio
 nal Laboratory and was promoted to associate professor at Stony Brook Univ
 ersity in 2020.\n\nProf. Liu's Ultrafast & Near-field Infrared Laboratory 
 explores the future of materials science using advanced infrared and THz n
 ear-field microscopy and nano-Fourier transform IR spectroscopy. Their nan
 oscale imaging and manipulation of light-matter interactions boasts a spat
 ial resolution over 1\,000 times higher than conventional optics. The lab 
 studies complex materials like transition metal oxides\, low-dimensional D
 irac/Weyl microstructures\, superconductors\, and multiferroics by accessi
 ng the native length and time scales of electron and lattice motion and mo
 nitoring energy excitations\, unlocking the mysteries of Mott physics and 
 other many body effects and bringing closer to practical applications.
GEO:42.449741;-76.481209
LOCATION:Clark Hall\, 700
SUMMARY:LASSP & AEP Seminar: Mengkun Liu (Stony Brook)
URL;VALUE=URI:https://events.cornell.edu/event/lassp-aep-seminar-mengkun-li
 u-stony-brook
CATEGORIES:Seminar
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