CDQT Guest Seminar: Self-Intercalated Covalent 2D magnets and heterostructures

Guest seminar hosted by CDQT unit.
Speaker: Prof. Hao Zeng (University at Buffalo, the State University of New York)
Title: Self-Intercalated Covalent 2D magnets and heterostructures
 

Abstract:
The realization of two-dimensional van der Waals (vdW) magnets by exfoliation down to the atomic limit has rekindled interest in 2D magnetism. However, most existing research has focused on exfoliated vdW systems, limiting chemical diversity and tunability. In this talk, I will introduce a lesser-explored material class known as covalent 2D magnets. These materials emerge from the self-intercalation of native 3d transition metal cations between layers of transition metal dichalcogenides, forming atomically thin, covalently bonded layered magnets denoted by the chemical formula M_1+dX₂. The degree of self-intercalation provides a unique tuning knob for exchange coupling, magnetic order, and spin texture. I will begin by discussing the synthesis of these materials, focusing on Cr2Te3, as well as 2D magnet/semiconductor heterostructures. Subsequently, I will uncover a new mechanism underlying the unconventional anomalous Hall effect (AHE) observed in such systems, driven by the nodal structures in the electronic bands modulated by the noncollinear spin texture. Finally, I will discuss how we leverage such a mechanism to realize reversible switching of the polarity of AHE by solid-state ionic gating.

About the speaker:
Hao Zeng is the Moti Lal Rustgi Professor in the Department of Physics at University at Buffalo (UB), the State University of New York. He received his B.S. degree in Physics from Nanjing University, China, in 1993, and his Ph.D. in Physics from the University of Nebraska-Lincoln in 2001. From 2001 to 2004, he was a postdoctoral fellow at the IBM Thomas J. Watson Research Center. He joined UB as an Assistant Professor and was promoted to full Professor in 2014. Dr. Zeng is a fellow of the American Physical Society and the American Association for the Advancement of Science, and a recipient of the Fulbright Fellowship and NSF CAREER Award. He is the Editor-in-Chief of Journal of Magnetism and Magnetic Materials. He has published 160 papers, which have been cited 25,000 times. His current research interests include nanoscale magnetism and spintronics, bio-applications of magnetic nanoparticles, and unconventional chalcogenide semiconductors.