Understanding and Controlling Magnetic Two-Dimensional Crystals

Non-technical Description Magnetic materials have found widespread applications in communications, computing, and advanced electronics. Electrons possess have intrinsic magnetism, due to a quantum property called spin. Magnetism in a bulk materials arises from the coupling of these spins to be oriented along the same direction. This research project explores the properties of a new class of ultrathin magnets based on two-dimensional (2D) materials. For such atomically thin materials, the orientations of electron spins are very sensitive to the local environment and external stimulus. This gives rise to new physical phenomena and device functionality not possible from conventional magnets. This project will study the effects of adsorbed molecules, adjacent layers, and mechanical strain on the properties of 2D magnets. The goal is to learn how to control their properties, potentially leading to the creation of on-demand physical properties and devices with ultracompact form factors and novel functionality. High school, undergraduate, and graduate students will be trained with a rich set of expertise in 2D materials fabrication and characterization. This project will therefore help to prepare the future workforce for the quantum information science and technologies in the U.S. The PI will also raise the public literacy of quantum technologies through local educational activities. Technical Description Magnetic 2D materials provide an ideal condensed matter platform for the study of quantum magnetism, and the control of 2D magnets potentially unlocks unprecedented opportunities for new quantum phases of matter and ultrathin magnetoelectric and magneto-optical devices. The breadth of application prospects of 2D magnets hinges on the diversity of magnetic properties but remains hindered by the status quo: only a small number of 2D ferromagnets have been unambiguously discovered, with a limited variety of properties. Through designing experiments to finely modify the structural, electronic, and chemical characteristics of 2D magnets, this project seeks to unravel the complex dependence of 2D magnetism on the basic physical parameters of quantum materials. Based on these fundamental understandings, vital engineering approaches can be developed to create “designer” or “on-demand” magnetic quantum materials properties. The main research approaches include controlling 2D magnets by subjecting them to practical influencing factors such as contacting materials, adsorbed chemicals, and strained lattices and probing the altered properties by a range of microscopies and spectroscopies such as scanning magnetic circular dichroism and the magneto-reflectance spectroscopy. Understanding 2D magnetism in relation to these influencing factors and developing engineering approaches therefrom could prompt unprecedented manipulation of 2D magnets, thereby transforming the magnetic quantum material landscape and enabling disruptive spintronic and quantum technologies. 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.