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<p class="MsoNormal"><b><span style="font-size:12.0pt;font-family:"Arial",sans-serif">Please join us for the Colloquium with
<span style="color:black;background:white">Dr. Liuyan Zhao, University of Michigan</span><o:p></o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:12.0pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:12.0pt;font-family:"Arial",sans-serif">Tuesday, Nov.16 at 3:45pm, on Zoom<o:p></o:p></span></b></p>
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<p class="MsoNormal"><b><span style="font-size:12.0pt;font-family:"Arial",sans-serif">Come for snacks in the Atrium at 3:30pm<o:p></o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:12.0pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></b></p>
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<span style="font-size:12.0pt;font-family:"Helvetica",sans-serif;color:black">Please use the Zoom link below to attend virtually:</span><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif"><o:p></o:p></span></p>
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<span style="color:black"><a href="https://osu.zoom.us/j/94858307115?pwd=K0JDMTROWVhIOUp6bU1sU0prZjNUZz09"><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif;color:#BB0000">https://osu.zoom.us/j/94858307115?pwd=K0JDMTROWVhIOUp6bU1sU0prZjNUZz09</span></a></span><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif;color:#555555"><o:p></o:p></span></p>
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<span style="font-size:12.0pt;font-family:"Helvetica",sans-serif;color:black">Meeting ID: <strong><span style="font-family:"Helvetica",sans-serif">948 5830 7115</span></strong></span><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif"><o:p></o:p></span></p>
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<span style="font-size:12.0pt;font-family:"Helvetica",sans-serif;color:black">Password: <strong><span style="font-family:"Helvetica",sans-serif">PRB1080</span></strong></span><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif"><o:p></o:p></span></p>
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<span style="font-size:12.0pt;font-family:"Helvetica",sans-serif;color:black">Faculty Host:
<span style="background:white">Rolando Valdés Aguilar</span></span><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif"><o:p></o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:12.0pt;font-family:"Arial",sans-serif"><o:p> </o:p></span></b></p>
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<b><span style="font-size:18.0pt;font-family:"Helvetica",sans-serif;color:black">Collective excitations in two-dimensional magnetic atomic crystals and moiré superlattices</span></b><b><span style="font-size:18.0pt;font-family:"Helvetica",sans-serif"><o:p></o:p></span></b></p>
<p class="MsoNormal" style="margin-bottom:12.0pt;background:white"><b><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif;color:black">Abstract</span></b><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif;color:black">: Two-dimensional
(2D) magnetism has been long sought-after since its theoretical investigations in the 1960s–1970s. It is only very recently that 2D magnetism is realized in magnetic atomic crystals and further tailored in magnetic moiré superlattices. Due to the small sample
sizes of atomic and moiré crystals, traditional diffraction-based techniques become extremely challenging, and advanced optical spectroscopy techniques turn out to be uniquely suitable for probing magnetic properties in 2D magnets – both static and dynamic
ones. In this talk, we will focus on collective excitations of 2D magnetism probed by magneto-Raman spectroscopy. Using CrI</span><sub><span style="font-size:9.0pt;font-family:"Helvetica",sans-serif;color:black">3</span></sub><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif;color:black"> atomic
crystals as an example, we will discuss four types of collective excitations in it: phonon for lattice, magnetism-coupled phonon for static magnetic order, magnon for dynamic magnetic excitations, and polaron for phonon-dressed excitons [1-4]. Then applying
such acquired knowledge into twisted double bilayer CrI</span><sub><span style="font-size:9.0pt;font-family:"Helvetica",sans-serif;color:black">3</span></sub><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif;color:black"> moiré superlattices,
we will reveal an unexpected net magnetization and potentially noncollinear spin textures that are absent in the layered antiferromagnetic CrI</span><sub><span style="font-size:9.0pt;font-family:"Helvetica",sans-serif;color:black">3</span></sub><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif;color:black"> bilayer
and four-layer films [5].</span><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt;background:white"><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif;color:black">References</span><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt;background:white"><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif;color:black">[1] <b>Physical Review X</b> 10, 011075 (2020)</span><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt;background:white"><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif;color:black">[2] <b>Proceedings of the National Academy of Sciences</b> 117, 24664 (2020)</span><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt;background:white"><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif;color:black">[3] <b>Nature Communications</b> 11, 4780 (2020)</span><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt;background:white"><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif;color:black">[4] <b>ACS Nano</b> 15, 10444 (2021)</span><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt;background:white"><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif;color:black">[5] <b>Nature Physics </b>in press (2021)</span><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt;background:white"><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt;background:white"><b><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif;color:black">More about Dr. Zhao:</span></b><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt;background:white"><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif;color:black">Dr. Liuyan Zhao received her PhD in physics from Columbia University in 2013 and her postdoctoral training at California
Institute of Technology in 2013–2016, before joining the University of Michigan in 2017. Her current research interest at Michigan focuses on studying electronic and magnetic phases in 2D and 3D quantum materials, using linear and nonlinear, static and ultrafast,
elastic and inelastic optical spectroscopy and microscopy techniques. Her selected awards include NSF CAREER, AFOSR YIP, Bryan R. Coles Prize, and Alfred P. Sloan Research Fellowship.</span><span style="font-size:12.0pt;font-family:"Helvetica",sans-serif"><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#333333"><img border="0" width="224" height="45" style="width:2.3333in;height:.4687in" id="x_Picture_x0020_1" src="cid:image001.png@01D7D488.298B6140" alt="The Ohio State University"></span><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#333333"><br>
</span><b><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#BB0000;background:white">Ruth Leonard</span></b><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#333333"><br>
Executive Assistant to the Chair<br>
</span><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#BB0000;background:white">Department of Physics</span><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#333333">
<br>
Physics Research Building, 191 West Woodruff Ave, Columbus, OH 43210<br>
614-292-5018 Office<br>
</span><a href="mailto:leonard.469@osu.edu"><span style="font-size:9.0pt;font-family:"Arial",sans-serif;background:white">leonard.469@osu.edu</span></a><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#333333">
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