SSCU-PHYS Joint Seminar Series
Speaker: Prof. Je-Geun Park,
Department of Physics & Astronomy, Seoul National University, Korea
Topic: Van der Waals magnets- opportunities and challenges
Date & Time: Wednesday, 18 January 2023 at 4.00 pm
Venue: Physics Auditorium
The modern history of magnetism is full of great advances in our knowledge of strong correlation. The list of materials that have been used is long and rich, but most of them are three-dimensional. It is not because materials with lower dimensions are less interesting but because such examples are relatively rare in nature: which is true at least until 2015. Not surprisingly, there have been consistent efforts to overcome this natural limit regarding two-dimensional (2D) magnetism: one notable example is thin films grown by a pulsed laser deposition technique. Although one should acknowledge thin films’ important contributions to the 2D magnetism and correlation studies, however, better access to naturally occurring materials would be more beneficial in these challenging, otherwise exciting endeavours.
Against this backdrop, in 2016, my group made several first successful reports of van der Waals magnets being exfoliated down to monolayer [1,2,3]: many new opportunities these materials might offer were immediately discussed, too . We have since witnessed enormous sea changes in the research landscape of van der Waals magnets. The initial report of 2D Ising magnetism on monolayer antiferromagnetic FePS3  was followed by similar reports on ferromagnetic Cr2Ge2Te6  and CrI3 . In this talk, I will give an overview of the field with several more recent highlights[8, 9].
Topic: Quantum materials: questions and challenges?
Date & Time: Friday, 20 January 2023 at 4.00 pm
Venue: Physics Auditorium
There is a saying I heard as a young PhD student in the early 90s that, like everything else in human culture, specific fields of science have their ups and downs in time. I later learned too that a new topic emerges as a new champion in each scientific field every ten years, capturing the critical questions of the times. Quantum material is arguably the buzzword of the times, ever increasingly used in the materials science community. It is not surprising in the era of quantum science and technology, especially given the enormous amount of funding pouring into anything quantum. Therefore, there is a general tendency for one to jump on the popular bandwagon. As one of the few who coined quantum materials in the early 2010s, I do not deny this criticism. Nevertheless, I would also like to put my thought into a more serious discussion by summarising what I see as scientific questions and challenges ahead of us. In this talk, I will present a somewhat personal view of the question in front us, and list a few challenges we need to solve collectively.
 Cheng-Tai Kuo et al., Scientific Reports 6, 20904 (2016).
 Jae-Ung Lee et al., Nano Lett. 16, 7433 (2016).
 Sungmin Lee et al., APL Materials 4, 086108 (2016).
 Je-Geun Park, J. Phys. Condens. Matter 28, 301001 (2016).
Cheng Gong et al., Nature, 546, 265 (2017).
 Bevin Huang et al., Nature, 546, 270 (2017).
 Kenneth S. Burch, David Mandrus, and Je-Geun Park, Nature 563, 47 (2018).
Soonmin Kangetal., Nature 583, 785 (2020).
Jun-Yi Shanetal., Nature 600, 235 (2021).