Abstract
From low-dimensional quantum materials to the recently discovered nickelate superconductors, the discovery of new material systems has continually driven advances in condensed matter physics. In this talk, I will introduce the concept of topotaxy as a new paradigm for quantum materials design. By employing low-temperature structural and chemical transformations that largely preserve the parent crystal framework, topotactic approaches overcome the limitations of conventional equilibrium synthesis and enable access to metastable phases that are otherwise difficult to realize. Using cuprate and nickelate superconductors as representative examples, I will demonstrate how topotactic approaches enable the discovery and design of new quantum materials. In cuprate superconductors, cryogenic strain engineering provides a sensitive means to continuously tune charge order and uncover its intricate interplay with superconductivity. In nickelate superconductors, topotactic chemical transformations have enabled the realization of new superconducting nickelate phases and revealed their underlying electronic structure. Together, these examples illustrate how topotaxy provides a powerful route for exploring metastable quantum materials beyond the reach of equilibrium synthesis. I will conclude by discussing emerging opportunities where topotactic materials design may lead to the next generation of quantum materials and new condensed matter phenomena.
Bai Yang Wang is currently a Postdoctoral Scholar in the group of Professor Zhi-Xun Shen at Stanford University. He received his B.S. in Applied Mathematics, Engineering, and Physics from the University of Wisconsin–Madison in 2016 and his Ph.D. in Physics from Stanford University in 2022 under the supervision of Professor Harold Y. Hwang, where he subsequently continued as a postdoctoral researcher. His research focuses on the design, synthesis, and characterization of quantum materials, with particular expertise in epitaxial growth of complex oxide thin films, low-temperature topotactic synthesis, unconventional superconductivity, transport measurements, and angle-resolved photoemission spectroscopy (ARPES). His recent work has centered on cuprate and nickelate superconductors.