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SUMMARY:Giant Circular Dichroism Driven by Particle–Hole Symmetry Breaki
 ng in MnBi2Te4
DTSTART:20260909T023000Z
DTEND:20260909T033000Z
DTSTAMP:20260925T082000Z
UID:indico-event-5274@indico-tdli.sjtu.edu.cn
DESCRIPTION:Speakers: Xiang Yuan (East China Normal University)\n\nHost: 
 Prof. Nanlin Wang \nVenue: TDLI Meeting Room N400\nTencent Meeting link:
   https://meeting.tencent.com/dm/S9Zepa8bxdZz \nMeeting ID: 692449779\, 
 no password\n \nAbstract:\nCircular dichroism\, arising from the differen
 tial interaction of circular polarized photon between chiral light and mat
 ter\, plays an important role in applications such as molecular sensing an
 d optical communications. However\, the intrinsic circular dichroic respon
 ses in most materials are typically weak and limited to narrow spectral ra
 nges\, especially in the infrared regime.\nIn this talk\, I will introduce
  an intrinsic giant circular dichroism induced by particle-hole asymmetry 
 in the type-II Weyl semimetal Mn(Bi1-xSbx)2Te4. By employing high-field in
 frared spectroscopy\, we observe sharp Landau-level optical transitions em
 erging in the ferromagnetic phase. These transitions originate from the in
 trinsic band-nesting effect associated with the type-II Weyl electronic st
 ructure. A k·p model reveals that the particle-hole symmetry breaking in 
 MnBi₂Te₄ arises from ferromagnetism-induced asymmetric spin-orbit coup
 ling. The substantial difference between the Fermi velocities of the condu
 ction and valence bands reconstructs the wavefunction characteristics of L
 andau levels\, resulting in optical transitions that strongly couple to on
 e circular polarization while being nearly forbidden for the opposite pola
 rization. Polarization-resolved magneto-infrared spectroscopy experimental
 ly confirms this pronounced circular polarization selectivity and further 
 reveals its broadband response.\nOur work demonstrates that particle-hole 
 symmetry breaking provides an effective route toward realizing polarizatio
 n-selective optical functionalities in quantum materials. I will also intr
 oduce recent developments of high-field infrared spectroscopy instrumentat
 ion.\n \nBiography:\nXiang Yuan received his B.S. and Ph.D. degrees in Ph
 ysics from Fudan University in 2014 and 2019\, respectively. He joined the
  State Key Laboratory of Precision Spectroscopy at East China Normal Unive
 rsity in 2019.\nHis research focuses on experimental studies of topologica
 l quantum materials under magnetic fields\, with an emphasis on the develo
 pment of advanced high-field infrared spectroscopy techniques. His major a
 chievements include the discovery of one-dimensional Weyl fermions\, three
 -dimensional van Hove singularities\, and giant circular dichroism effects
  in quantum materials.\nHe has published representative works as the first
  or corresponding author in Nature and 3 Nature Materials. He has been rec
 ognized as the MIT Technology Review Innovators Under 35\, received the Ju
 nhao Youth Scientist Award.\n \n\nhttps://indico-tdli.sjtu.edu.cn/event/5
 274/
LOCATION:Tsung-Dao Lee Institute/N4F-N400 - meeting room (Tsung-Dao Lee In
 stitute)
URL:https://indico-tdli.sjtu.edu.cn/event/5274/
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