Magnetism, Spin Texture and Magnetotransport Phenomena in Covalent 2D Magnets

Non-technical Description This research project explores the properties of a new class of magnetic materials with thicknesses of only a few-atomic layers. Conventional two-dimensional (2D) materials like graphene are made of atomic layers weakly bound to each other. The materials to be studied here have extra atoms that are covalently bonded to the individual layers, acting like a glue to hold the atomic layers together and change the way they behave. The exotic properties of these 2D magnets make them particularly interesting for fundamental scientific research and practical applications. The ultimate goal is to control their properties through material design, electric fields, and physical strain. This project will help to pave the way for novel memory and logic devices operating at ultrafast speed with low power consumption. Such devices could impact applications such as sensing and quantum information processing. The investigators will strive to broaden the participation of underrepresented groups by mentoring and targeted recruiting. The partnership between the University at Buffalo and Bryn Mawr College will enable the participation of female undergraduate students through summer exchange and research experiences at national facilities. Technical Description This research program symbiotically combines the expertise of the investigators to synthesize new self-intercalated covalent 2D magnets and magnet/semiconductor heterostructures, and to explore and tune emergent spin-based topological and magnetotransport phenomena. The project objectives are (1) to grow high-quality, large area covalent 2D magnets and related heterostructures by chemical vapor deposition and dative epitaxy; (2) understand the mechanisms of real space spin textures and momentum space Berry curvature, their correlation with self-intercalated cation concentration, and the effects of their intertwining on electrical carrier transport; and (3) achieve active control of spin-based topological phenomena in real and momentum space by electric gating, strain, and foreign ion intercalation. The rich phases achievable by varying the concentration of self-intercalated cations in these covalent 2D magnets and their interactions with different vdW templates provide broad material design parameter space that could bestow new spin properties unattainable in existing magnetic materials. This project will advance the fundamental understanding of these materials, decipher the effects of intertwined spin structures and Berry curvature on magnetotransport, and expand the library of materials to chemically stable covalent 2D magnets with a high Curie temperature. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.