Physics Seminar

“Probing 3D Structure and Physical Properties of Materials at the Single-Atom Level”

Dr. Yongsoo Yang

Dept. of Physics and Astronomy, UCLA

April 11 (Wed), 1:30pm

#1323 (E6-2, 1^st fl.)

Abstract:

Modern science and technology rely on functional materials, and the physical properties of these materials often strongly depend on defects, local disorder, nanoscale heterogeneities, and grain structures at the atomic scale. Traditional crystallography, which is reliant on periodicity, has been the main method for determining crystal structures, but cannot determine defects or other non-crystalline features. My work goes beyond crystallography. Without any prior assumption of underlying structure, atomic electron tomography (AET) is now able to locate the 3D coordinates of individual atoms with picometer precision and with elemental specificity [1-3]. I will show a variety of complex atomic structures with 3D atomic-level details; including grain boundaries, chemical order/disorder, phase boundaries, and anti-site point defects. I will further demonstrate that these experimentally determined atomic structures can be combined with quantum mechanical calculations to provide an atomic-level understanding of physical properties such as 3D strain tensors, magnetic moments and local magnetocrystalline anisotropy. Understanding the relationship between atomic structure and physical properties will open up new avenues in condensed matter physics and allow the rational design of novel materials at the atomic scale [1-2].

[1] Yang et al., Nature 542, 75-79 (2017).

[2] Xu et al., Nature Mater. 14, 1099-1103 (2015).

[3] Pryor*, Yang* et al., Sci. Rep. 7:10409 (2017).

Contact: Yongseop Kang, Administration Team (T.2599)

Department of Physics