seed projects

Bharat Jalan, Tony Low: Strain-Engineered Ti-alloyed RuO₂ for Metal-Insulator Transitions and Tunable Magnetic States.

Phase diagram of the RuO₂-TiO₂ system showing the bulk miscibility gap contrasted with the reduced miscibility achieved in thin-film form. The accompanying schematic of the hybrid MBE system illustrates our synthesis strategy to stabilize and grow fully miscible Ru_1-xTi_xO₂ epitaxial films.

This Seed project explores how chemical alloying and epitaxial strain can be used together to control the electronic and magnetic properties of rutile RuO₂. While bulk RuO₂ is typically a nonmagnetic metal, our recent studies have shown that epitaxial strain in ultrathin RuO₂ films grown on TiO₂ (110) can stabilize a new altermagnetic polar metallic state that does not exist in the bulk. However, this phase usually appears only in a fully strained films with critical thickness ≤ 4 nm. To extend this behavior to thicker and more scalable materials, we seek to study Ti_xRu_1-xO₂ alloys, where Ti substitution allows us to tune the lattice structure and electronic interactions. Guided by DFT calculations, we will synthesize high-quality Ti_xRu_1-xO₂ films using hybrid MBE across a wide range of compositions. This work will help reveal how alloying and strain together control metal-insulator transitions and magnetic behavior, opening new pathways for oxide-based spintronic materials.

Funded by the National Science Foundation through the University of Minnesota MRSEC under Award Number DMR-2011401