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SUMMARY:Anomalous Hall effect from spin-group symmetry breaking
DTSTART;VALUE=DATE-TIME:20260508T020000Z
DTEND;VALUE=DATE-TIME:20260508T030000Z
DTSTAMP;VALUE=DATE-TIME:20260503T021900Z
UID:indico-event-4991@indico-tdli.sjtu.edu.cn
DESCRIPTION:Speakers: Yang Gao（高阳） (University of Science and Tech
 nology of China)\n\nHost: Prof. Anyuan Gao  Venue: TDLI Meeting Room N4
 00Tencent Meeting link: https://meeting.tencent.com/dm/eSa1BHPr3jvN Meet
 ing ID: 881924098\, no password Abstract:The anomalous Hall effect is one
  of the most fundamental phenomena in solid state physics. Traditionally\,
  it is viewed as a time-reversal-symmetry-breaking phenomenon and the resu
 lting conductivity is governed by the Onsager’s reciprocal relation\, i.
 e.\, . In experiments\, such relation is generally taken at the linear ord
 er of \, yielding an empirical law employed in many previous literatures. 
 However\, in strong magnets\, the exchange energy associated with the magn
 etic order is usually comparable with other energy scales\, rendering such
  power series expansion over  to be inappropriate. In this talk\, I will s
 how that it is more informative to reformulate the anomalous Hall effect a
 s a spin-group-symmetry-breaking phenomenon by treating the spin-orbit cou
 pling as perturbation\, since the latter is usually much smaller than exch
 ange and hopping energy. Associated with the spin-group-symmetry-breaking\
 , the anomalous Hall effect can exhibit various multipolar anisotropy when
  the spin order is rotated globally. Our theory applies to ferromagnets\, 
 collinear and non-collinear antiferromagnets. Out of equilibrium\, such mu
 ltipolar anisotropy contains antisymmetric component\, which corresponds t
 o an anomalous Hall current driven by coherent spin wave. Such a signal ca
 n be used to probe altermagnets that normally do not show an anomalous Hal
 l effect.  Biography:Professor Yang Gao got his bachelor’s degree from
  Peking University in 2009. He then joined Prof. Qian Niu’s group in Uni
 versity of Texas at Austin and got his doctor’s degree in 2016. After th
 at\, he joined Prof. Di Xiao’s group in Carnegie Mellon University as a 
 postdoctoral research associate. In 2020\, he joined University of Science
  and Technology of China. Professor Gao’s research focuses on Berry phas
 e effect in nonlinear and nonreciprocal transport and optical phenomena. H
 e has published about 30 papers\, with 12 of them in Physical Review Lette
 rs\, Nature\, Nature Communications\, and PNAS. \n\nhttps://indico-tdli.s
 jtu.edu.cn/event/4991/
LOCATION:Tsung-Dao Lee Institute/N4F-N400 - meeting room (Tsung-Dao Lee In
 stitute)
URL:https://indico-tdli.sjtu.edu.cn/event/4991/
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