Physics Colloquium: Tailoring Properties in Two-dimensional Materials via Structural Design

Prof. Xiuquan Zhou, Georgetown University

Abstract: Materials chemistry is pivotal in developing advanced materials with applications in semiconductors, energy, and quantum materials. However, conventional solid-state synthesis methods are incapable of supporting advanced materials design. Therefore, my research is dedicated to creating new synthetic methods to tailor material properties. In this presentation, I will demonstrate the complementary roles of chemistry and physics by using the newly discovered KNi₄S₂ as an example.¹ KNi₄S₂ is a topological metal with a Dirac cone near its Fermi surface. By deintercalating K, we can suppress its topological behavior and induce antiferromagnetism.  Complete removal of K from KNi₄S₂ resulted in a new antiferromagnetic van der Waals binary Ni₂S with T_N = 25K. Moreover, the structure and physical properties can be further adjusted using a new hydroxide-based high-temperature solution.^{2, 3} I will demonstrate the successful insertion of various two-dimensional metallic and ionic layers into KNi₄S₂, resulting in products with superconducting, semiconducting, and magnetic properties depending on the intercalates used. This case exemplifies that material properties can be tailored for specific functions through structural design, which was made possible through the advancement of synthetic methods.

1.X. Zhou, D. J. Mandia, H. Park, M. Balasubramanian, L. Yu, J. Wen, A. Yakovenko, D. Y. Chung and M. G. Kanatzidis, Journal of the American Chemical Society 143 (34), 13646-13654 (2021).

2.X. Zhou, C. D. Malliakas, A. A. Yakovenko, B. Wilfong, S. G. Wang, Y.-S. Chen, L. Yu, J. Wen, M. Balasubramanian, H.-H. Wang, D. Y. Chung and M. G. Kanatzidis, Nature Synthesis 1 (9), 729-737 (2022).

3.X. Zhou, V. S. C. Kolluru, W. Xu, L. Wang, T. Chang, Y.-S. Chen, L. Yu, J. Wen, M. K. Y. Chan, D. Y. Chung and M. G. Kanatzidis, Nature 612 (7938), 72-77 (2022).