Effects of epitaxial strain on the electronic and vibrational structure of rutile oxides: Insights from computational modeling

Discovering materials with higher superconducting transition temperatures (T_c) remains a central challenge in condensed matter physics. Progress towards this goal requires a systematic exploration of how material parameters influence normal-state electronic structure, and, subsequently, how this structure affects superconducting properties. Both of these relationships are essential, yet neither is fully understood. Epitaxial strain can induce superconductivity in RuO₂ thin films grown on TiO₂ substrate, with a T_c of about 2 K [Nature Communications 12, 59 (2021)]. Moreover, varying the orientation and magnitude of strain significantly alters this T_c​. This highlights epitaxial strain as a tunable and experimentally accessible parameter for systematically engineering higher-T_c materials. In this work, we use density functional theory (DFT) to predict the effects of epitaxial strain on the electronic band structure and phonon spectra of other rutile oxides, namely RhO₂, thereby offering key insights into the relationship between strain and superconductivity while helping focus experimental efforts on the most promising candidate materials.