Colloquium - Liuyan Zhao (Univ of Michigan) - Collective excitations in two-dimensional magnetic atomic crystals and moiré superlattices

November 16, 2021

3:45PM - 4:45PM

Virtual Zoom link below

Add to Calendar 2021-11-16 16:45:00 2021-11-16 17:45:00 Colloquium - Liuyan Zhao (Univ of Michigan) - Collective excitations in two-dimensional magnetic atomic crystals and moiré superlattices Collective excitations in two-dimensional magnetic atomic crystals and moiré superlattices Dr. Liuyan Zhao University of Michigan Virtual only Faculty Host: Rolando Valdés Aguilar Abstract: 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 CrI3 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 CrI3 moiré superlattices, we will reveal an unexpected net magnetization and potentially noncollinear spin textures that are absent in the layered antiferromagnetic CrI3 bilayer and four-layer films [5]. References [1] Physical Review X 10, 011075 (2020) [2] Proceedings of the National Academy of Sciences 117, 24664 (2020) [3] Nature Communications 11, 4780 (2020) [4] ACS Nano 15, 10444 (2021) [5] Nature Physics in press (2021) More about Dr. Zhao: 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. Please use the Zoom link below to attend virtually: https://osu.zoom.us/j/94858307115?pwd=K0JDMTROWVhIOUp6bU1sU0prZjNUZz09 Meeting ID: 948 5830 7115 Password: PRB1080 Virtual Zoom link below OSU ASC Drupal 8 ascwebservices@osu.edu America/New_York public

Add to Calendar 2021-11-16 15:45:00 2021-11-16 16:45:00 Colloquium - Liuyan Zhao (Univ of Michigan) - Collective excitations in two-dimensional magnetic atomic crystals and moiré superlattices Collective excitations in two-dimensional magnetic atomic crystals and moiré superlattices Dr. Liuyan Zhao University of Michigan Virtual only Faculty Host: Rolando Valdés Aguilar Abstract: 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 CrI3 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 CrI3 moiré superlattices, we will reveal an unexpected net magnetization and potentially noncollinear spin textures that are absent in the layered antiferromagnetic CrI3 bilayer and four-layer films [5].   References [1] Physical Review X 10, 011075 (2020) [2] Proceedings of the National Academy of Sciences 117, 24664 (2020) [3] Nature Communications 11, 4780 (2020) [4] ACS Nano 15, 10444 (2021) [5] Nature Physics in press (2021)     More about Dr. Zhao: 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.     Please use the Zoom link below to attend virtually: https://osu.zoom.us/j/94858307115?pwd=K0JDMTROWVhIOUp6bU1sU0prZjNUZz09 Meeting ID: 948 5830 7115 Password: PRB1080   Virtual Zoom link below Department of Physics physics@osu.edu America/New_York public

Collective excitations in two-dimensional magnetic atomic crystals and moiré superlattices

Dr. Liuyan Zhao
University of Michigan

Virtual only

Faculty Host: Rolando Valdés Aguilar

Abstract: 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 CrI₃ 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 CrI₃ moiré superlattices, we will reveal an unexpected net magnetization and potentially noncollinear spin textures that are absent in the layered antiferromagnetic CrI₃ bilayer and four-layer films [5].

References

[1] Physical Review X 10, 011075 (2020)

[2] Proceedings of the National Academy of Sciences 117, 24664 (2020)

[3] Nature Communications 11, 4780 (2020)

[4] ACS Nano 15, 10444 (2021)

[5] Nature Physics in press (2021)

More about Dr. Zhao:

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.

Please use the Zoom link below to attend virtually:

https://osu.zoom.us/j/94858307115?pwd=K0JDMTROWVhIOUp6bU1sU0prZjNUZz09

Meeting ID: 948 5830 7115

Password: PRB1080