What are the key degrees of freedom for the next generation of quantum functional materials?

The emergence of new quantum degrees of freedom provides an opportunity for the development and breakthrough of performance bottlenecks in functional materials for modern applications. This article provides an overview of quantum functional materials, including magnetic materials, optical materials, and topological materials, based on electron transport, orbital angular momentum, and spin coupling degrees of freedom. Spin degrees of freedom mainly affect the applications of magnetic materials in storage and computing fields, while orbital angular momentum degrees of freedom demonstrate high-dimensional degrees of freedom in optical devices with potential breakthrough applications in areas such as optoelectronic detection and sensing. The unique bulk-surface separated electron transport properties of topological materials can be applied to topological insulators, topological superconductors, and other fields. The application prospects of quantum functional materials are very broad, and finding new degrees of freedom and quantum degrees of freedom in traditional materials is an important opportunity for advancing technological development and transformation. Further theoretical research and the development of high spatial and temporal resolution, in situ spectroscopic detection methods will help discover more quantum functional materials and promote their applications.