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.