Collaborative Research: RUI: Topologically protected magnetic phases in Heusler alloys

Non-technical Abstract: The magnetic properties of materials originate from the magnetic atoms that compose them. These atoms act like tiny bar magnets. In materials such as iron, the atomic magnets align parallel to one another, much like compass needles pointing in the same direction. However, in some materials, the atomic magnets arrange themselves in non-parallel, or non-collinear, configurations. These arrangements arise from the interplay between the crystal structure and intrinsic interactions among the magnetic atoms. Certain non-collinear magnetic structures possess topological properties—unique geometric characteristics that make them robust against deformation and disruption. This topological protection holds significant promise for applications in information storage and quantum computing. This project combines experimental and theoretical approaches to study topologically protected magnetic structures, aiming to identify materials that could serve as platforms for future quantum technologies. Our research focuses on a remarkable class of compounds known as Heusler alloys—chemical combinations of several metals, including magnetic elements like iron. Recent discoveries have shown that Heusler alloys with specific crystal structures can support non-collinear magnetic arrangements. Due to their relative ease of synthesis and tunable magnetic properties, Heusler alloys offer a conducive environment for the discovery of topologically protected magnetic phases. In addition to advancing quantum science, this project will provide undergraduate and graduate students with vital experience in cutting-edge quantum research, helping train the next generation of quantum scientists and engineers. Technical Abstract: The main goal of this project is to identify the relationship between crystal structure, chemical composition, electronic band structure, and topologically protected magnetic states to design / discover novel quantum materials from the Heusler family of alloys. These materials are actively studied for practical applications such as spintronics, quantum information science and engineering, data storage, magnetic cooling, shape memory and magnetocaloric devices. Exploring topologically protected magnetic phases, such as skyrmions and antiskyrmions, as well as other forms of magnetic non-collinearity in Heusler compounds for obtaining fundamental understanding of these phenomena, which can then be applied to the development of practical device applications including novel data storage mechanisms, constitutes the main research objective of this project. The main hypothesis of this project is that Heusler materials with tetragonal crystal structure may exhibit non-collinear magnetic order, which may in certain cases result in topologically protected magnetic phases, such as skyrmions and antiskyrmions. The research team is using various experimental and theoretical techniques to perform the project, such as arc-melting, physical vapor deposition, Lorentz transmission electron microscopy (LTEM), electron-transport measurements, and density functional theory (DFT) calculations. The project aims to uncover the underlying physical principles of topological magnetic states and other forms of magnetic non-collinearity in Heusler materials. This allows the research team to identify / discover mechanisms to control these properties by intrinsic chemistry change or other forms of external stimuli (such as mechanical strain) leading to the discovery of new quantum materials exhibiting such properties. 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.