Materials discovery requires new tools that enable design principles. The properties of many technologically relevant materials, such as perfect conductivity in superconductors and electric current control of magnets, arise from the spin of electrons. This project will use pseudospin - a quantum mechanical degree of freedom analogous to electron spin - as a new tool for materials discovery. The research will follow the collaborative and iterative closed-loop Materials Genome Initiative approach by combining analytic and predictive computational theory, together with epitaxial growth of materials one atomic layer at a time, and characterization using advanced microscopy and spectroscopy techniques. This project will develop new guiding principles based on controlling pseudospin in materials design, a paradigm shift in quantum materials discovery that will enable both superconductors that can sustain high magnetic fields and novel magnets. This activity will provide training for the next-generation quantum workforce.