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CATEGORIES:Lecture
DESCRIPTION:The family of monolayer two-dimensional (2D) materials hosts a 
 wide range of interesting phenomena\, including superconductivity\, charge 
 density waves\, topological states and\nferromagnetism\, but direct evidenc
 e for antiferromagnetism in the monolayer has been lacking. Nevertheless\, 
 antiferromagnets have attracted enormous interest recently in spintronics d
 ue to\nthe absence of stray fields and their terahertz resonant frequency. 
 Despite the great advantages of antiferromagnetic spintronics\, controlling
  and directly detecting Neel vectors have been challenging. In my talk\, I 
 will show that we have developed a sensitive second harmonic generation (SH
 G) microscope and detected long-range Neel antiferromagnetic (AFM) order do
 wn to the monolayer in MnPSe3 and the bilayer in MnPS3 . In MnPSe3\, we obs
 erved the switching of an Ising type Neel vector reversed by the time-rever
 sal operation. We rotated them by an arbitrary angle irrespective of the la
 ttice by applying strain. By studying both a Landau theory and a microscopi
 c model\, we conclude that the phase transition in the presence of strain i
 n MnPSe3 falls into the Ising universality class instead of the XY type and
  the Ising Neel vector is locked to the strain. In MnPS3\, we observed the 
 Heisenberg-type domain switching\, and we also observed an anomalous layer-
 dependent mirror symmetry breaking.\nFinally\, we found that the 180 deg AF
 M domain walls in both compounds are highly mobile\, paving the way for fut
 ure control of the antiferromagnetic domains by strain or external fields\n
 on demand for ultra-compact 2D AFM terahertz spintronics.\nReferences:\n1. 
 Ni et al. Nature Nanotechnology 16\, 782-787 (2021)
DTEND:20211122T213000Z
DTSTAMP:20260313T224219Z
DTSTART:20211122T203000Z
LOCATION:
SEQUENCE:0
SUMMARY:Focused Topic Seminar Series: Liang Wu\, University of Pennsylvania
UID:tag:localist.com\,2008:EventInstance_38190592608959
URL:https://events.bc.edu/event/focused_topic_seminar_series_liang_wu_unive
 rsity_of_pennsylvania
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